August Tips
Monthly tips are categorized by To-Dos, What to Plant, or Pests and Diseases. Scroll through the list to see items in each category. Also, refer to our list of tips useful for any month.
August tips
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1. To-do
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Eliminating Perennial Weeds
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To control perennial weeds, repeatedly cultivate soil in summer and, when possible, keep the soil completely dry for several months to dehydrate weed stems, rhizomes, or tubers.
- June, July, August -
Drought Tips - Vegetable Gardening
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- Plant only as much as you can use. Produce that isn’t harvested wastes water.
- Plant in groups or triangular patterns rather than straight rows. This lets you water more efficiently, and the plants form a leafy canopy that shades the soil.
- Mulch, mulch, mulch to decrease moisture loss and reduce competition from weeds.
For more information: Ten Tips for Vegetable Gardening during a Drought
- May, June, July, August -
Firescaping
- After a dry winter, we must be careful about the fire season. Choosing plants carefully and maintaining them well can help to reduce the risk, especially for homes closer to the hills or actually in the hills. Two relevant landscaping principles are fuel reduction and fire path interruption. With fuel reduction, choosing succulents or other water retaining plants will slow a fire down. On the other hand, plants that are dry or have high oil content, such as eucalyptus, juniper, and pine, give the fire fuel to burn hotter and faster. Interrupting the fire path involves spacing plants to avoid a line along which a fire can easily travel. Minimize plantings close to the house. East Bay Municipal Utility District offers a free firescaping booklet that you can download from their website.More Information: Firescaping Zones
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Squash
- Summer squashes are meant to be picked and eaten when they are small and tender. These include zucchini, crookneck, chayote, patty pan, and papaya pear squash. Winter squash is grown at the same time as summer squash. What makes it different is that it develops a harder rind that allows it to be stored long term to be used throughout the winter. It can also remain on the vine longer before harvesting. Some examples are butternut squash, pumpkins, and Tahitian squash. Squash plants should be in the ground by now and may already be producing fruit. Continue to water and fertilize them throughout the season and control weeds to ensure maximum production. If squash grows a few inches and starts to wither, it is probably not getting pollinated; you can manually transfer pollen from the male flowers (on stalks) to the female flowers (on developing fruit). An overabundance can be prepared for freezing or shared, or plants can be pulled out early to make room for the next season’s planting.More Information: Summer Squash, Winter Squash
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Water Budgeting
- We always need to use water wisely. Sometimes it is necessary to stop and think about your landscape and prioritize water use. Trees are a long-term investment, yet mature trees may have extensive root systems enabling them to find enough water on their own. Fruit trees may need watering approximately monthly during the summer in order to produce good fruit. Vegetables should always be given adequate water in order to fulfill their purpose in the garden; otherwise the little bit of water you used will have been wasted if the garden is not feeding you well. It’s helpful to understand that home-grown vegetables use much less water overall than ones purchased at the store. Established flowering shrubs, especially California natives, tend to need less water than annual flowers and maybe a more water-efficient way to have color and beauty in your garden. Lastly, keep the weeds under control so that they don’t rob water from the plants that you actually want.More Information: Water Use Classification of Landscape Species (WUCOLS)
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Irrigate in Circles and Spirals
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For more information: Help Your Trees Survive the Drought
- May, June, July, August -
Drought Tip - No Fertilizer
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More information: Skip fertilizing
- May, June, July, August -
Testing Soil Moisture Depth
- You know how long you water your garden, but do you know how deep the water is going? You don’t need an expensive moisture meter to check. A simple probe can help you find out. Use any item sturdy enough to push a foot or so into the soil, for example, a long screwdriver or metal rod. Push the probe directly into the soil using firm pressure. It will go through moist soil and stop when it hits the underlying dry soil, showing you how deep your water has penetrated. Watering deeply but infrequently is recommended.
More information: Checking Moisture Depth
- June, July, August -
Time for Seed Saving
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More information: How to Save Seeds
- August, September, October -
Protect Native Bees
- You probably see non-native honeybees in your garden, but do you know there are over 1600 species of native bees in California? These bees don’t make honey, don’t live in hives (most live right in the ground), and are much less likely to sting since they have no colonies to defend. Research shows some species pollinate crops twice as effectively as honeybees, plus they’re best suited to pollinate native plants. But like honeybees, they’re threatened by pesticides and loss of habitat. Help preserve these species by growing a variety of plants that flower at different times of the year and by keeping areas of open ground in your yard.
More information: Native Bees and Their Favorite Plants
Native Bee images, clockwise from top left: Leafcutter bee (Jim McCulloch), carpenter bee (Kathy Keatley Garvey), long-horned bee (Kathy Keatley Garvey), sweat bee (Missouri Department of Conservation Staff)
- March, April, May, June, July, August -
Pinching Flowers and Herbs
- More Information: Pinching Flowers and Herbs
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Pinch Your Basil
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More information: Basil Care
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Drought Tip - Lawns
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More information: Drought Resources
- March, April, May, June, July, August, September, Any month -
Harvesting Oranges
- There’s a simple way to know whether your citrus fruit is ripe: taste it! Citrus varieties differ in when they first ripen and how long the fruit holds on the tree. Harvest dates depend on the variety and the climate. For example, the normal fruit season is winter for Navel orange, and summer for Valencia orange. Until you are familiar with your particular tree, sample a fruit periodically to see if it suits your taste. Allow fruit to ripen fully on the tree, as citrus does not continue to ripen once it’s picked.
More information: Harvesting and storing citrus
- January, February, July, August, September, October, November -
Transplanting Vegetables
- More information: Vegetable Planting Handbook (Los Angeles Master Gardeners)
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Drought Tip - Irrigate Efficiently
- Water restrictions are being put into place all over the state due to the current drought. With over half of urban water used in landscapes, it is essential to make sure your irrigation system is efficient. Watch your plants for signs of underwatering, overwatering, or uneven watering. Consider reducing irrigation times. And make sure your water bill hasn’t unexpectedly jumped. Also, adjust systems on timers monthly as the weather changes or use an automatically-adjusting smart controller. A smart controller can make the needed adjustments after initial programming with plant, location, and other relevant information. Our Santa Clara County clay soil absorbs water slowly, so only water for a few minutes at a time to avoid runoff. Then repeat until the water penetrates to the depth of the roots. Inspect drip and sprinkler systems regularly to make sure there are no leaks, emitters are not clogged and it is watering the plants and not the sidewalk, also make sure the water is going to the root zones of the plants. If you run a hose to a plant, set a kitchen or cell phone timer so you don’t forget that the water is running. Valley Water can help residents with Water Wise Outdoor Surveys and Landscape Rebate Programs.
More information: Irrigation System Audit
- March, April, May, June, July, August, September, Any month -
Tomato Bottom Scarring
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Sometimes scarring can be seen on the bottom (blossom end) of tomatoes. This can be caused by weather conditions such as cool and cloudy weather at bloom time, making the blossom stick longer to the small fruit. The fruit is perfectly good to eat with the damaged part cut out. Some large heirloom tomatoes are more susceptible to this condition.
Also known as catfacing.
- June, July, August -
Hand Pollinating Squash
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If the squash grows a few inches and then starts to die, it’s probably because the pollination wasn’t successful.
More information: Fruit Setting Problem in Cucurbits
- July, August -
Pruning Hydrangeas
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For better-looking hydrangeas, prune out the spent blossoms. Hydrangeas are fast growing and need pruning to control size and shape. Cut out the older stems that have flowered, leaving the ones that have not flowered. For the biggest flower clusters, reduce the number of stems. For lots of medium size flowers, keep more stems.
- August -
Water the Roots, Not the Plants
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It's tempting to get the hose out and spray your dry, thirsty plants, but you don't want to waste water. Keep their feet nice and cool, but resist the urge to squirt the leaves unless they need a cleaning (for dust or white fly for instance).
It's a common belief that daytime water on the leaves will burn them. While it's possible, according to scientists—for hairy leafed plants where water droplets are held above the leaf surface—but not very likely. It's more the water will simply evaporate and not do your plants much good and could encourage fungal pathogens if wet overnight.
- June, July, August -
Fruit Tree Harvest
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If you have fruit trees that are ready to pick and more fruit than your family can use, please contact Village Harvest. Village Harvest is a non-profit volunteer organization in the greater San Francisco Bay Area that harvests fruit from backyards and small orchards, then passes it along to local food agencies to feed the hungry. They also provide education on fruit tree care, harvesting, and food preservation.
- July, August -
Encouraging Dahlia Blooms
- First, make sure those tall flowers have support so they don’t flop over or break off. Disbudding—removal of all but the central bud on each stalk—will result in larger more spectacular flowers. Deadheading—cutting the spent flowers back to one node below the bloom before they can set seeds—will encourage lateral blooms. Water the plants regularly, and continue to apply low nitrogen fertilizer throughout the summer.Fundamentals of Growing Dahlias , American Dahlia Society
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Summer Vegetables
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More information: Vegetable gardening
- May, June, July, August, September -
How to Tell if Fruits and Vegetables Are Ready to Pick
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The UC Davis Postharvest Technology website was designed for commercial growers, but the information on how to tell When Fruits and Vegetables are Mature is handy for home gardeners as well. There's also information about how to Store Fruits and Vegetables for Better Taste.
- July, August, September -
Preserving Fruits and Vegetables
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Interested in how to preserve fruits and vegetables? UC Food Safety has lots of information including "Safe Handling of Fruits and Vegetables", "Safe Methods of Canning Vegetables", "Chart on Storing Fresh Fruits and Vegetables", and more. Visit their web page UC Home Preservation and Storage Publications for more details.
- August, September -
Fresh Fruits and Vegetables Without a Garden!
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If you like the freshest possible produce but don't have the space or time to grow your own, find a certified Farmers Market selling directly to consumers. The County of Santa Clara website has a Farmers Market page with links to certified Farmers Markets.
- June, July, August, September -
Keep Up With Your Vegetable Harvest
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The middle of summer is a particularly busy time of year for vegetable gardeners. It can be a challenge to keep up with harvesting—beans can become swollen and tough and zucchinis can become baseball bats! It's particularly important to keep up with plants such as beans because the production of mature seeds (inside the pod) signals the plant to stop producing. Tomatoes can split and rot on the vine in exceptionally hot weather.
- July, August -
Consider Dehydrating Some Of Your Harvest
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If you have more fruit than you know what to do with, dehydration can be an excellent way to preserve it. Apricots, apples, pears, figs, and tomatoes are all great candidates for drying. While making jams, jellies, cobblers, and pies is one way to use up an abundant harvest, they add fat and sugar to our diet, dried fruit can be a healthy alternative! Onions and garlic can also be dehydrated to last indefinitely.
Also see the publication on Dehydrating Basics by the UCCE Master Food Preservers of Amador/Calaveras Counties.
- August, September -
Gather Herbs for Drying
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Itching to do something in the garden but not sure what? Cut back some of your oregano or mint and dry it. In our climate you will likely have herbs year-round, but drying some can help you when times are busy, or perhaps your relatives in the mid-west would love some home-grown, dried herbs, for a holiday gift this year. Simply hang it upside down in a cool, dry place. Why not try putting some on a cookie sheet on your dashboard to make use of the hot temperatures in your car without turning on an oven or a dehydrator?
- August -
Clean Up Fallen Fruit
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Pick up fallen fruit daily to prevent attracting critters or diseases. If your fruit is being eaten at night then rats are the likely culprit, if it's during the day it may be squirrels. Holes, rather than bites, are made by birds. In addition to harvesting regularly, ripening fruit can be protected with a netting fine enough to exclude birds and small animals
- July, August -
Prune Apricot and Cherry Trees
- August is the best time to prune apricot and cherry trees in our area. By pruning at least six weeks before the first fall rains, you reduce the chance of Eutypa dieback. The disease is caused by a fungal parasite caused by airborne spores that enter fresh pruning wounds. Cankers develop around an infected wound and eventually can kill a tree if not managed.
Pruning in August instead of earlier causes less regrowth, which means less wasted energy for you and the tree. If you pruned during the rainy season in past years, you should check your trees for Eutypa infection and prune limbs at least one foot below any visible infection.- July, August
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Grass Cycling
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Leave the clippings on the lawn when mowing. This provides nitrogen for the lawn. Mow frequently so that no more than 1/3 of the length of the grass blade is cut in any one mowing. Grass decomposes rapidly and very little thatch is formed. Small amounts of thatch can actually be beneficial to a lawn, serving as a mulch. Many parks and golf courses have been doing this for years. Other uses for grass clippings include mulching for weed control and as a great addition to your compost pile. There are some cities that no longer will allow grass clippings in their dumps.
- June, July, August, September -
Soil Moisture Test
- How can you tell if your soil is moist enough?
- For trees or other landscaping, try pushing a soil probe or rod into the ground. When it stops going in, that shows how deeply water has penetrated. Irrigate until the water reaches 12 inches deep for grass, 12 to 18 inches for shrub and perennials, and 12 to 24 inches for trees.
- For garden beds or pots, use a trowel or simply stick your finger down into the soil a few inches to feel if it is moist or dry. Irrigate to keep the root zone moist.
- For smaller pots, you can often tell by lifting them if they need water. Well-watered pots will be heavy. Watch out for pots that have become hydrophobic, where the water runs through them without getting absorbed. They will need to be watered very slowly or soaked in a larger container to get rehydrated. See our tips for dealing with hydrophobic soil.
Remember that plant roots need air as well as water, so you want your soil to be moist but not soggy. -
Fertilizing Ornamentals During Drought
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One way to manage plants during drought is to reduce the amount of fertilizer used. While plants need nutrients to survive and be healthy, excess fertilizer promotes additional growth, which then demands more water.
- May, June, July, August -
Watering Hydrophobic Soil
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Just as a dry sponge repels water, overly dry soil can do the same thing. This dried out soil is called hydrophobic. Hydrophobic soil can waste a lot of water as water drains away from the plant's root zone.
In pots: learn more about how to re-wet very dry soil on our Watering Hydrophobic Soil page. In the yard: setting sprinklers to run for 5 minutes, waiting for the water to soak in, and then running for a longer time can prevent water loss due to hydrophobic soil.
- May, June, July, August -
Lady Beetle
- We all know that lady beetles are good for the garden. Make sure you can recognize the larval stage because this life stage eats even more aphids than the adult form. Lady beetles lay their distinctive yellow eggs near a food source such as aphids. The larvae grow quickly, then pupate into the familiar adult form (but there are actually many varieties of lady beetles). It’s better to attract lady beetles to your garden rather than buying and releasing them. Purchased lady beetles generally fly away, and the process of collecting them in the wild is often destructive. To attract lady beetles, refrain from spraying insecticides, grow flowers that attract beneficial insects, and leave some aphids for them to eat.
For more information: Aphid Eaters
- March, April, May, June, July, August -
Lawn Care
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Make sure you are mowing to a height appropriate for your type of grass. Mow frequently enough so that only one-third of the leaf is removed at any one time.
Fertilizing is important, even if you are grasscycling, which only provides about 20% of a lawn's fertilizer needs. Grass is all leaf so the primary nutrient needed is nitrogen. Keep on top of weed removal.
Thatch is the layer of living and dead grass material (blades, rhizomes, stolons) that can build up on the surface of the lawn. A thin layer protects the soil surface and shallow roots from drying out from the sun, but a thick layer prevents water from getting through. You can remove dead grass material on the soil surface with a special thatch rake to allows water to reach the roots more easily.
More Information: The UC Guide to Healthy Lawns
- May, June, July, August, September, October -
Soil Solarization
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Soil solarization can be used to control diseases, nematodes and weeds by baking everything under plastic sheeting.The best time for solarization of soil is from June to August. Transparent or clear plastic is the best choice. Leave the soil covered for 4 –6 weeks. Refer to the UC Pest Note on Soil Solarization for Gardens & Landscapes.
- June, July, August -
Composting
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Composting is a good way to repurpose yard and kitchen waste, and it provides a free method to feed plants and improve soil structure. If you are unsure about how to begin composting, take a look at this simple how-to compost page. You can also go to the UCCE Composting Education Program website to learn more about free two-hour classes offered throughout the county.
As the weather warms up, compost piles dry out faster. Keep compost piles as damp as a wrung-out sponge to keep organisms alive and working on decomposing yard waste. Turning the pile to incorporate more oxygen also supports life in the compost pile.
- June, July, August, Any month -
Watering Trees
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The amount of water trees need in the summer depends in large part on the age of the tree. Newly planted trees with shallow roots may need weekly water. Trees that are a few years old and fairly well established may need monthly watering. Mature trees with extensive root systems may not need any supplemental water. These are just VERY general guidelines. It is essential to know the water requirements of the plants. You can determine these by researching cultural needs or knowing their native habitats, the soil type and how well it retains water, and the micro-climate in which the tree is located, e.g., shaded, windy, dry. The UC WUCOLS database has information on the water needs of over 3,500 plants used in California landscapes. Always water slowly and deeply to penetrate down to the roots. Use a soaker or drip hose around the tree at the drip line and let it slowly drip for 2 to 3 hours. Don't let lawn sprinklers hit tree trunks as this may cause crown rot and damage the tree.
- July, August, September -
Deadheading
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Deadheading means removing spent blossoms from your plants. Not all plants need deadheading, but if the flowers stay on the plant and become unattractive (think roses, dahlias, marigolds, coneflowers, geraniums and many more), then consider a little pruning. The technique varies by plant; some spent flowers can be snapped off by hand (dahlias), others are better done with hand pruners (roses), and some can be sheared off all together (lavender). You'll not only make the plant look better, you'll stimulate additional blooming for plants that have a long blooming season.
- May, June, July, August, September -
Drought Tip - Laundry to Landscape Irrigation
- A laundry to landscape system is an easy way to save water in times of drought. It can be installed easily at a low cost to send rinse water from clothes washers directly to the landscape.
Suitable plants include fruit and ornamental trees, shrubs, and ornamental annuals. It’s not applicable where the water would come in direct contact with fruits or vegetables.
More information: Laundry-to-Landscape Graywater System
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Garden Sanitation
- Keeping the garden clean can help keep it healthy. Remove spent blossoms, fruit, and other plant parts as your plants finish producing. Dead and decaying plant parts can attract pests and give them safe places to breed. Insect pests damage plants directly by eating material or sucking out juices and nutrients, and they also spread diseases between plants as they move around. Weeds compete with desirable plants for water and nutrients and even sunlight, so remove them promptly. Older leaves of some plants, like squash vines, may naturally turn yellow and die. Removing them early allows the plants’ energy to go into the actively growing parts. Pick up fallen fruit that can attract rodents and can also return disease pathogens to the soil and plant. It’s particularly important to remove dried-up fruit “mummies” so that the fungal spores don’t spread. Prune dying tree branches before they can fall and do damage. Some flowering plants will produce more flowers if you remove spent blooms, a process called deadheading. You can leave healthy fallen leaves in place to form a mulch and decompose naturally, or you can rake them up and add them to the compost pile with other disease-free plant material. Do not compost diseased material.
More information: What Does Plant Disease Sanitation Really Mean?
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Drought Tip - Trees Come First during Drought
- More information: Tips to Keep Trees Alive
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Drip Irrigation
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- Water is placed more accurately and efficiently in the root zone, it is applied at a slow rate that reduces loss from runoff.
- Dry soil between plants allows you to work in the garden between irrigating.The key to success is watering long enough to supply adequate water to the root zone. Inappropriate watering commonly damages landscape plants. As with any irrigation system, they are efficient only when soil around the plants being irrigated is regularly monitored for proper moisture levels (Reference: UC Pest Note Poor Water Management, Poor Drainage).
- April, May, June, July, August, September, Any month -
Fertilizing Fruit Trees
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As fruit starts to develop, trees and vines use nutrients to help with this energy-intensive task. This is a good time to plan a strategy for fertilizing your trees.
In the first year, a very light application of nitrogen (N) is desirable for most soils. Do not make first year applications before six to eight inches of new growth occurs. Split applications are safest, one or two months apart, so one application might be made this month.
After the first year: research indicates that summer fertilizer applications (August to mid-September) are more efficient than late winter (traditional) applications.
Fully mature fruit trees may not need fertilizing. Read more at UC Home Orchard Fertilization page.
- February, August -
Weed Spotlight - Bindweed
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For more information: Field Bindweed Pest Notes
- March, April, May, June, July, August, September, Any month
2. What to plant
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Peas
- An old American tradition says that planting peas on St. Patrick’s Day will bring good luck at harvest time. But the best planting date actually depends on the climate where you live. Planting on St. Patrick’s Day in the northeast may lead to a second planting weeks later when frost gets the first batch. Yet in warmer climates like ours, we can plant weeks earlier and may even be eating peas from the garden on St. Patrick’s Day. (We can also plant them here in the fall.) You may want to soak the seeds overnight to help get them ready to germinate. They can be planted directly in the ground, about half an inch deep. Keep the seeds evenly moist until they start to sprout. Provide a trellis or some kind of support for the vertical vines if you are growing pole peas; bush peas can stand on their own.
More Information: Peas
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Don't Plant an Invasive Plant
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According to PlantRight, so-called invasive plants "escape into open landscapes and cause a variety of ecological problems. They displace native plants and wildlife, increase wildfire and flood danger, clog valuable waterways, degrade recreational opportunities, and destroy productive range and timberlands."
PlantRight has identified the following as invasive in Northern California: Green fountain grass (Pennisetum setaceum), Periwinkle (Vinca major), Pampas grass (Cortaderia selloana), Highway iceplant (Carpobrotus edulis), Mexican feathergrass (Stipa / Nassella tenuissima), Yellow Flag Iris (Iris pseudacrorus), Water Hyacinth (Eichhornia crassipes).
With just a little research you can avoid using plants that are unfriendly to the Bay Area. -
Cool-Season Vegetables
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If starting from seed, August is the time to start seedlings for fall vegetables. Broccoli, cauliflower, beets, and fennel will take about 6 weeks to grow to transplant size. Greens such as lettuce, spinach, arugula, chard, and kale will be ready in 4 weeks. So for planting in mid-to-late September, aim to start them in early to mid-August. You can direct seed them on the ground if you have the space. The soil should still be warm enough for seeds to germinate but shade them from the hottest afternoon sun, and keep the seeds moist.
If buying transplants from a nursery, you can wait until September. In Santa Clara County, many of the cool-season crops that are planted in September or October can be planted again in February and March. You can get in another crop before it's time to put summer vegetables in the ground.
A big advantage of cool-season vegetables is that they need less supplemental water due to lower temperatures, fewer daylight hours, and rain. There are also fewer pest problems in the winter. Cool-season vegetables grow well in temperatures ranging from 55°F to 75°F, at locations with 6–8 hours daily of sun.
Check out our videos page for videos on cool season vegetables, including a 3-session course for more inspiration.- August, September, October -
Seed Viability
- Seed packets have a “packed for” date on the back. Yet seeds can still be viable for years beyond that date if stored correctly. Ideal storage conditions are cool and dry. The older the seeds are, the lower the germination rate will be. So plant more of the older seeds than the number of plants you ultimately want. You can do a germination test by putting seeds on a damp paper towel and enclosing them in plastic to keep them uniformly moist. Do this right before planting time so you can transplant the ones that successfully germinate. Or you can take your chances and just plant them directly and see what comes up. If you are saving your own seeds, make sure to choose seeds from the healthiest plants.
Whenever it's hard to find flower seedlings, if you have some old flower seed packets, you can scatter the seeds randomly in a section of your yard and enjoy whatever flowers.
More Information: Vegetable Seed Viability -
Vegetable Planting Chart
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Wondering what vegetables can be planted now? To get the best success—whether planting from seed or transplants—refer to our Santa Clara County Vegetable Planting Chart. It's based on our own garden experiences.
- February, March, May, June, July, August, October, Any month -
Selecting Seeds
- While curled up inside the warm, dry house poring through seed catalogs, how do you decide among all the delightful descriptions? First, be clear on the purpose of your garden. Are you trying to grow exotic food? Do you want to attract native butterflies? Are you interested in flowers you can cut and bring inside? Next, think about the conditions of your site. Is it warm and sunny or is there a lot of shade? Do you have heavy clay soil? Choosing seeds that do well in your area makes for healthier plants with less work. At this point, you have the parameters within which to choose what tickles your fancy. If you would like to save seeds in the future, then choose open-pollinated seeds, including heirlooms. Heirlooms are open-pollinated seeds that have been around for multiple generations. Otherwise, you can plant hybrids that have the best traits of their parent plants but will not reproduce true to type from saved seeds. Follow planting directions on the packet for the best results.
More Information: Seed Saving
3. Pests and Diseases
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Identifying Beneficial Insects
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More information: Beneficial Insects
- March, April, May, June, July, August, September -
Spiders in Your Garden
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More information: Arachnophobia Video
- August, September, October, November -
White Butterflies and Green Caterpillars
- Have you seen these small yellowish-white butterflies fluttering around? Cabbage white butterflies feed on many flowers, but for laying their eggs. They favor the cabbage family, such as broccoli, cauliflower, and mustard. The velvety green caterpillars, also called imported cabbageworms, feed on the leaves after hatching. While mature plants tolerate a few holes munched in their leaves, young seedlings don't have foliage to spare. Cultural controls include handpicking the caterpillars, brushing the eggs off the undersides of leaves, and using row covers to protect the seedlings. UC lists additional options in the link below.
More information: Managing Imported Cabbageworms
- March, April, May, June, July, August, September, October, November -
Bug Patrol
- It’s never helpful to have critters competing with you for your food. Damage can be done by squirrels, raccoons, rats, birds, and caterpillars, yet it is the tiniest creatures that can be the hardest to detect. That’s why it’s helpful to do a regular inspection, as often as once or twice a day if possible. Knowing what it is will help you figure out what to do to maximize the productivity of your garden. Some pests are out during the day and others do their damage at night, so you may want to take a flashlight out at non-peak gardening hours. Holding a piece of white paper under a plant and shaking the plant can make insects fall off for identification. The most common place to find pests is on the undersides of leaves so make sure to closely inspect those parts. A magnifying glass of some sort is a useful tool. You can also take a picture with your cell phone and then zoom in for a closer view. It’s important to be able to recognize the eggs, the larval and nymph stages, and the adult form, and to be able to differentiate between beneficial insects and harmful pests. Don’t indiscriminately squish everything that moves! Once you have done your detective work, you can go to the University of California IPM website for identification and management tips, or contact the Master Gardener Help Desk for guidance.More Information: Beneficial Predators – These are the ones you want!
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Tomato blossom end rot
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A brown depression on the bottom of tomatoes is usually blossom end rot (BER). This disorder is related to a calcium deficiency aggravated by irregular watering. Since most soils have adequate calcium, watering is usually the problem. Without regular watering, the calcium in the soil cannot reach the plant. Mulching can help. Water tomatoes regularly. Avoid flooding them so the roots sit in water. For more detailed information about BER please view Managing Blossom-End Rot in Tomatoes and Peppers.
- July, August, September -
Pepper Weevil
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More information: Pepper Weevil
- July, August, September -
Cottony Cushion Scale
- Scale insects populate the stems or branches of plants and suck out the nutrients. Some are soft and some are armored during part of the life cycle. Cottony cushion scale is a soft variety that is often seen on apple trees. The crawlers are reddish and the females develop elongated white egg sacs on their backs, but it is most likely the molting skins that look like cotton that will alert you to their presence. Small infestations can sometimes be wiped off with gloved fingers. Natural predators may also move in to take care of the problem. There are beetles and parasitic flies that can provide good control. Keeping ants out of the tree will also help because ants will protect the pests in order to be able to eat their sugary exudate.
More information: Cottony Cushion Scale Pest Note
- June, July, August -
Tomato Russet Mite
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Tomato russet mites deplete juice from the cells of leaves, stems and fruit. They usually start at the base of the plant and move upward. If not controlled, these pests can kill plants. At first sign of damage, treat with sulfur dust or a spray solution of wettable sulfur and spreader-sticker. More information is found in the UC Pest Note on Tomato Russet Mite.
- June, July, August -
Ant Control
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On outdoor and sometimes indoor plants, ants protect and care for honeydew-producing insects such as aphids, soft scales, whiteflies, and mealybugs, increasing damage from these pests.
Ants are among the most prevalent pests in households. UC IPM offers steps to follow in an Ant Emergency.
Ant management requires diligent efforts and the combined use of mechanical, cultural, sanitation, and often chemical control methods. It is unrealistic and impractical to attempt to totally eliminate ants from an outdoor area. Focus your management efforts on excluding ants from buildings or valuable plants and eliminating their food and water sources. Reducing outdoor sources of ants near buildings will reduce the likelihood of ants coming indoors.
Ants on Trees and Shrubs
When numerous ants are found on plants, they are probably attracted to the sweet honeydew deposited on the plants by honeydew-producing insects such as aphids or soft scales. Ants may also be attracted up into trees or shrubs by floral nectar or ripening or rotten sweet fruit. These ants can be kept out by banding tree trunks with sticky substances such as Tanglefoot. Trim branches to keep them from touching structures or plants so that ants are forced to try to climb up the trunk to reach the foliage.
When using Tanglefoot on young or sensitive trees, protect them from possible injury by wrapping the trunk with a collar of heavy paper, duct tape, or fabric tree wrap and coating this with the sticky material. Check the coating every one or two weeks and stir it with a stick to prevent the material from getting clogged with debris and dead ants, which will allow ants to cross. Ant stakes with bait can also be used around trees.For more information about what ant baits and insecticides to use, please consult the UC Pest Note on Ants.
- June, July, August, Any month -
Ailing Ornamental Trees
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If you have an ailing tree, here are some questions you can ask yourself to begin diagnosing the problem: is the entire canopy of the tree affected? If the answer is yes, you can reasonably guess that something is wrong below the soil. A lack of nutrients (refer to the UC Pest Note on Mineral Deficiencies) will likely cause the leaves to either die (necrosis) or lose color (chlorosis). Too much or too little water will also cause foliage problems (See UC Pest Note on Poor Water Management, Poor Drainage).
If only parts of the tree are affected, it is likely your problem is above ground. Is there a pattern to the distress? You can rule out or suspect sunscald by determining which side of the tree faces the harshest sun (UC Pest Note on Sunburn).
What kind of tree is it? Is there new growth? If there is, that’s a great sign that a single event rather than an ongoing problem distressed your tree. The UC IPM website will direct you to species-specific pests and disorders to begin diagnosing your tree's ailments.
- August, Any month -
Moles
- You and the moles will probably never see each other: they won’t see you due to very poor vision and you won’t see them because they live underground. But you will see the damage they do. Unlike gophers which eat plant roots, moles eat insects and worms. Yet they can do collateral damage to plant roots as they tunnel through in search of their preferred food. Plants can also suffer if the tunnels redirect water away from the roots when you try to irrigate. Moles create what look like mountain ridges as they tunnel through near the surface, and they leave behind round mounds of soil when they dive deep. The most effective way to manage them is to use traps specifically designed for moles.
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Stink Bugs
- Stink bug's eggs are white in barrel-shaped cylinders with concentric circles ending in a bull’s eye. You might find them on the underside of leaves or in plain sight on fruits and vegetables in your garden. Soon they will hatch, shapeshifting in appearance five times before becoming shield-shaped adults either in brown or green color. Called stink bugs because they excrete a smelly fluid when disturbed. These insects feed on a variety of fruits, nuts, and vegetables such as tomatoes, squash, and beans, leaving blemishes and dark pinpricks in their wake. The best way to control them is to handpick eggs and bugs off plants and get rid of weeds where they may live. It’s not helpful to use insecticides because by the time you notice damage, the stink bugs will likely be gone already.
More information: UC Pest Note on Stink Bugs
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Tomato Hornworm
- Both tomato hornworms and tobacco hornworms can do significant damage to tomato plants. They can eat entire leaves and take bites out of the fruit. Although they are large with a striking appearance, they camouflage themselves well on plants and can be surprisingly hard to find. Once you see one, you’ll wonder how you missed it. The first clue to their presence is often a pile of frass (insect larva excrement) on the leaves or ground under the pest. They are up to four inches long so they are easy to handpick for disposal. If you see a row of white eggs on their backs, those are from a parasitic wasp that will take care of the problem naturally. They are striking, with white striping and little round circles. The caterpillars get their name from the horn on their back end, and they are the larval stages of rather large brown moths.More information: Tomato Hornworms
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Rat Management
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Rats show up when your citrus, tomato, or fruit first starts to ripen. Rats are agile climbers and usually live and nest in shrubs, trees, and dense ground cover like ivy. One management strategy is to prevent access to the tree by cutting branches away from fences or other trees, leaving a gap of at least 2–3 feet, good sanitation is required. Garbage and garden debris should be eliminated. Use tight-fitting lids on garbage cans. Thin out dense vegetation to make the habitat less desirable. Mow ivy once a year to the ground. Climbing ivies on fences or buildings should be removed.
Per the UC pest note (linked below), trapping is the safest and easiest method for controlling rats. Read the pest note for other management strategies as well.
More information: Rat Management
- January, February, March, April, July, August, September, Any month -
Healthy Tomatoes
- Tomatoes are one of the most popular vegetables in home gardens, largely because of the taste difference between a homegrown tomato and a store-bought tomato. Here are a few things to watch out for to keep the plants healthy. Regular watering helps nutrients flow throughout the plant and can prevent blossom end rot. Clean soil and sanitation reduce the common Verticillium wilt in which lower and older leaves turn yellow and brown. And russet mite, where lower leaves and stems appear a greasy bronze, can be controlled with sulfur dust.
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Boxwood Blight
- Boxwood is an evergreen shrub typically grown as a short border hedge. It is often pruned in a straight, formal style. It has been falling out of favor as native, drought-resistant plantings are increasing in popularity. Another reason for reconsidering its use is the fairly recent arrival of a fungal disease called Boxwood Blight. It was first detected in the U.S. in Connecticut in 2011 and reported in Santa Clara County in 2017. It is spread by contact through pruning tools, gardeners’ clothing, and irrigation. This blight can show symptoms in as little as a week. Look for brown leaf spots with dark edges, white spores on the undersides of leaves, black lesions on stems, and severe dieback. Humidity and overhead watering contribute to the disease being able to take hold. Pruning infected branches, with sterilization of tools between each cut, may help. Fungicides cannot control the disease once it starts. More likely the plant will have to be removed, bagged, and thrown in the garbage.Boxwood Blight, Purdue Botany and Plant Pathology
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Powdery Mildew
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Powdery mildew likes warm days and cool nights. Unlike most other fungi, it does not need moisture to thrive. Early symptoms include yellow chlorotic spots on the leaves. The presence of the fungus becomes obvious as it starts to produce spores that look like white powder on leaves. Eventually, the leaves will turn brown and dry.
The best defense is to plant varieties that are resistant to powdery mildew. Also helpful is planting in full sun with good air circulation through the plants. Washing off the leaves, preferably in the morning, can buy some time. Powdery mildew generally affects the older leaves first, and you can remove these when they are too covered to be able to photosynthesize. Fungicides can help but you want to be careful about using them around something you are going to eat. At some point, the plant may decline so much that it needs to be removed.
More Information: Powdery Mildew on Vegetables -
Rose Care
- Roses are notoriously susceptible to many diseases, including rust, black spot, and powdery mildew. For this reason, they are often planted at the edges of vineyards to give an early warning about diseases that can affect the vines. Yet not everything that negatively impacts roses is a disease or pest, so don’t automatically reach for the chemicals. Abiotic disorders are caused by nonliving factors and can be addressed with cultural changes. Blackened areas on canes can be from sunburn. Brown-edged leaves may signal a high concentration of salt in the soil. Yellow leaves may be due to nutrient deficiencies. Deformed growth may be due to exposure to glyphosate, the active ingredient in Roundup. Good air circulation allows the morning dew to dry, and helps prevent rust and powdery mildew. Some practices to keep your roses healthy are to choose hardy varieties, enrich the soil with compost, fertilize regularly but not too much, irrigate directly to the root zone, and remove suckers (the rapid-growing, long canes) from roses. Prune them below the bud union.
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Codling Moth
- If you grow apple or pear trees, you may have noticed small holes in the maturing fruit and then discovered a worm inside. "Worms" in your apples are actually the larval form of the codling moth. Codling moth larvae can cause a great deal of damage to apples, pears, plums, and walnuts by penetrating the fruit and boring into the core.
Trees should be monitored every week for signs of infestation. Infested fruit should be removed and discarded to break the codling moth life cycle. Sanitation is an important non-chemical step in controlling this pest. Make sure to pick up fallen fruit promptly, and pick apples with holes that are still on the tree. This will keep future populations down.
Pheromone traps can be hung in isolated trees. But if you have just one apple tree don't bother. You will just attract codling moths to your tree.
Fruit can be bagged for protection, but this method is very labor-intensive. Heavy infestations may require the use of pesticides, but proper timing of sprays is critical. Read the UC Codling Moth Pest Note for more information.
- May, June, July, August -
Sooty Mold
- If your citrus leaves have a black coating, you may have a sooty mold problem. This black mold can also be seen on citrus fruit, avocado leaves, magnolia leaves, hibiscus, other host plants, and even on sidewalks beneath trees.
The sooty mold fungi grow on “honeydew”, a sticky substance excreted by plant-sucking insects such as aphids, scale, mealybug, and whitefly. They suck the sap out of plants and excrete excess sugars. It exists purely on the surface of a plant and is not a systemic issue. By itself, the fungi cannot kill the plant but it can coat the leaves to the extent that sunlight is prevented from reaching the leaf surface, thus reduce photosynthesis.
Ants protect the sucking insects from their predators so they can eat the honeydew. Keep ants out of trees and away from honeydew-producing insects by applying a sticky compound such as Tanglefoot on a tape wrapped around the trunk.
Pruning branches to allow better air circulation also helps. You can hose off the mold itself with a strong jet of water. And you can eat the fruit once you wash off the sooty mold.For more information, see Sooty Mold Management Guide. -
Birds
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Birds can cause extensive damage to tree fruit crops. Unlike squirrels, birds are more likely to peck at one piece of fruit until it’s gone. If they are doing too much damage, netting over a tree can keep them away from the fruit. If you use visual repellents (such as Mylar streamers or noisemakers) to frighten them, be sure to vary the method so that the birds don’t become immune to the effects. Read the UC Pest Note on Birds on Tree Fruits and Vines for more information.
- July, August, September -
Gophers
- Have you ever watched a plant wiggle and then disappear underground right before your very eyes? That’s the work of a gopher. You don’t often see them because they spend most of their time in underground tunnels, but you see the damage they do by chewing on plant roots or irrigation lines. One way to distinguish them from other soil-dwelling vertebrate pests is by the crescent-shaped mounds of dirt they make when they dive back down. Fresh mounds of moist soil are an indication of recent activity. They do not hibernate, so they are busy year-round. They can be eliminated through trapping and dispatching. Gophinator, Macabee, and Cinch traps specifically designed for gophers are the most commonly used. You can plant trees and shrubs in gopher baskets in the ground to protect their roots. You can also line the bottom of raised beds with hardware cloth to keep the gophers from burrowing up into the beds.
More information: Gopher Pest Note
- June, July, August, Any month -
Squirrel Control
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For more information: Pest Note on Tree Squirrels and Pest Note on Ground Squirrels.
- May, June, July, August, Any month -
Verticillium Wilt
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Verticillium wilt is a soil-borne fungal disease that damages plant veins. The damage is characterized by affecting one side of the plant. The leaves may wilt and turn brown, dying upward from the base of the branch to the tip. Dead leaves often fall, but may not. Mildly affected plants may survive if fertilized and encouraged into vigorous growth. The fungus can live for years in the soil.
Planting tomatoes, peppers, eggplants, and potatoes (all members of the Solanaceae or nightshade family) in the same place no more than once every three years helps reduce the fungal population to non-harmful levels. Soil solarization may eliminate Verticillium wilt from infected soils. Crop rotation with cereals or broccolis can reduce the pathogen. Avoid high nitrogen fertilizers. Plant Verticillium wilt-resistant varieties of tomatoes, potatoes or strawberries. Refer to the UC Pest Note information on Tomato, Potato, and Strawberry for species-specific suggestions.
- May, June, July, August -
Brown Marmorated Stink Bug
- Native to Eastern Asia, this pest was introduced to the United States in the 1990s and has been established in Santa Clara County. Some features to distinguish these bugs from other stink bugs are white stripes on the antennae, a blunt head shape, and smooth shoulder margins.
They feed and reproduce on a variety of plants and are particularly damaging to fruit. You can cut cosmetic damage off fruit and still eat the rest of the fruit. To keep out stink bugs, cover vegetable plants with row covers. You can pick the bugs off plants and squish them or knock them off into soapy water. They are attracted to light and can get into homes where if vacuumed up, they can stink up your vacuum bag.
More Information: Brown Marmorated Stick Bug Pest Note -
Deer
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Although there's no such thing as a deer-proof plant, some can be called deer-resistant. Plants with strong smells, woolly or hairy leaves, or prickly or thorny parts are less appetizing to deer. Other strategies include deer repellents, enclosing plants in wire cages, netting, or tall fences. Read more in the UC Pest Note on Deer and use our search for Deer Resistant Plants.
- August -
Giant Whiteflies
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If you see white beardlike filaments handing from the leaves of your hibiscus, bird of paradise, or other plants, you may have giant whitefly. Another sign is the distinctive wax spirals on the undersides of the leaves. They can usually be controlled by washing them off or removing affected leaves. For more information see UC Pest Note on Giant Whitefly.
- August -
Sunscald on Fruits and Vegetables
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Fruits and vegetables can get sunburned in the summer heat. This is more commonly called sunscald and it frequently affects peppers, tomatoes, and persimmons. The leaves shield the produce from the sun, so it helps to make sure the plants have sufficient fertilizer and water for a healthy plant. You can cut out the damaged parts and eat the rest of the fruit.
- July, August -
Bitter Pit (Brown Spots) on Apples
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Bitter pit is a physiological disorder that affects many varieties of apples. The condition develops after fruit has been picked. It is caused by low levels of calcium in fruit tissues which leads to small brown, sunken lesions that become dark and corky. Highly susceptible cultivars include Red Delicious, Granny Smith, Golden Delicious, Jonathan and Gravenstein. The UC Bitter Pit Pest Note recommends cultural practices for control.
For even more information, the UC Postharvest Technology Center website has grower information, including using calcium sprays starting in June.
- August, September -
Whiteflies
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Whiteflies are tiny, sap-sucking insects that may become abundant in vegetable and ornamental plantings, especially during warm weather. They excrete sticky honeydew and cause yellowing or death of leaves. Outbreaks often occur when the natural biological control is disrupted. Management is difficult once populations are high.
- June, July, August, September
Whiteflies use their piercing, needlelike mouthparts to suck sap from phloem, the food-conducting tissues in plant stems and leaves. Large populations can cause leaves to turn yellow, appear dry, or fall off plants. Like aphids, whiteflies excrete a sugary liquid called honeydew, so leaves may be sticky or covered with black sooty mold that grows on honeydew (See UC Pest Note on Sooty Mold). The honeydew attracts ants, which interfere with the activities of natural enemies that may control whiteflies and other pests.
Management of heavy whitefly infestations is difficult. The best strategy is to prevent problems from developing in your garden or landscape. In many situations, natural enemies will provide adequate control of whiteflies; outbreaks often occur when natural enemies are disrupted by insecticide applications, dusty conditions, or interference by ants. Avoid or remove plants that repeatedly host high populations of whiteflies.
In gardens, whitefly populations in the early stages of population development can be held down by a vigilant program of removing infested leaves or hosing down with water sprays. Reflective mulches can repel whiteflies from vegetable gardens, and yellow sticky traps can be used to monitor or, at high levels, reduce whitefly numbers. If you choose to use insecticides, insecticidal soaps or oils such as neem oil may reduce but not eliminate populations. Systemic insecticides may be more effective but can have negative impacts on beneficial insects and pollinators.
For more information see UC Pest Note on Whiteflies. -
Today’s Grubs Are Tomorrow’s Beetles
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More Information: What are White Grubs?
- April, May, June, July, August, September, October -
Giant Whiteflies
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Giant whiteflies were only discovered in California in 1992, but the infestation is now widespread in the San Francisco Bay Area. Plants most affected are ornamentals, such as begonia, hibiscus, bird of paradise, mulberry, and others. Adults produce spirals of wax primarily on the underside of leaves and lay their eggs in waxy bands which grow heavier as the population increases. Wax filaments grow to lengths of up to 2 inches, but in shielded areas, they can reach ten inches long! Even though affected plants weaken, they rarely die. Manage giant whiteflies by removing infected leaves, washing the undersides of leaves with strong streams of water, and encouraging beneficial insects to control populations.
More Information: Giant Whiteflies in Your Garden
- June, July, August, September