UC Master Gardeners, Santa Clara County, CA
University of California
UC Master Gardeners, Santa Clara County, CA

June 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.

1. To-do

  • Geranium Care -

    Geraniums need very little water. Too much water can lead to stem rot, or, if combined with too much fertilizer, more leaf growth than flowers. Geraniums prefer a dry location. If this isn't possible, try growing them in pots.

    - June
  • Citrus Fertilizing -

    Honeybee on citrus blossomIn California, most soils contain adequate nutrients for citrus growth, except nitrogen. One-year old trees will need 1/10 of a pound of nitrogen, while mature trees need approximately 1-1/2 pounds. These amounts should be divided into three different feedings in April, June and August.

    Blood meal without all the fillers is an excellent source of nitrogen, or you can purchase a balanced product that contains zinc. Spread the fertilizer evenly over the entire root area and water in.

    For more information, refer to the UC Pest Note on Fertilizing Citrus, and Questions and Answers to Citrus Management from the UC Davis Home Orchard website.

    - January, February, May, June
  • Composting -

    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
  • Bee Swarms -

    Bees are very active in warm weather. There is simply so much pollen and nectar to collect! Sometimes, a bee colony may swarm. If you see a swarm, don’t panic. As in any other time when working around bees, remain calm, move gently, and give them their space. Bees generally swarm when they are looking for a new home. Swarming bees are loaded with food and are not interested in stinging people. Contact the Bee Guild to have swarms removed.

    - May, June, July
  • Deadheading -

    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
  • Irrigation and Graywater -

    As temperatures rise, irrigation becomes more important. Container plants will begin to dry out and need to be checked every few days. Inspect irrigation systems for leaks, clogged drip emitters, misaligned sprinkler heads, and other problems which could waste water. Make sure the water is going to the root zones of the plants.

    Things to consider:

    Use a smart irrigation controller. These help adjust watering based on local conditions. Learn more about smart controllers.

    Collect water from the shower as it heats up and use it to water any plants.

    Use graywater from garage sinks and washing machines to water ornamentals and lawns. UC has a publication titled Use of Graywater in Urban Landscapes in California.

    - March, April, May, June, July, August
  • Mulch - a Gardener's Best Friend -

    Mulching around your plants has many benefits. It holds in moisture by reducing evaporation from the soil, keeps weed seeds from being able to germinate, and moderates the temperature of the soil so that it doesn't vary as much with direct sun and changes in air temperature. Mulching can cool the soil for plants like blueberries and it will help hold some heat in for summer vegetables as the air gets cooler.

    Mulch will guard against soil erosion when the rains start. Organic mulch such as wood chips or bark will slowly break down and improve your soil over time.

    It is recommended to keep mulch six inches away from trunks and twelve inches away from buildings. If you are confused about the difference between compost and mulch, then UCCE's Soil Management - Compost versus Mulch Comparison will help.

    Many local tree trimming companies are happy to deliver free wood trimmings that can excellent mulch - just be sure that the trimmings are disease- and palm- and eucalyptus- free. This can be hard to guarantee. Straw (not hay) from the local feed store can also be inexpensive, effective mulch.

    - May, June, July, August, September, Any month
  • Grass Cycling -

    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
  • Worm Composting -

    Worm compostingWorm composting also called vermiculture or vermicomposting is a convenient way to decompose kitchen waste and provide nutrient-rich soil amendments for your vegetable garden.

    Here is a description for Getting Started.

    The Santa Clara County Home Composting Education Program offers Worm Workshop classes.

    - February, June, September
  • Drip Irrigation -

    Low volume drip irrigation systemConsider various forms of irrigation conversion! Irrigation systems, especially drip and micro-sprinklers, have drastically improved over the last few years. For example, there are kits that convert pop-up sprinkler heads to low-flow systems. The conversion kits include a pressure regulator to control changes in pressure and a filter to improve water quality. Water usage is reduced through better water management, control of distribution and less loss from evaporation. Other advantages include :

    - 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
  • Tomato Staking -

    It's time to start planning how you will stake your tomatoes. You will want to stake your tomatoes right after you plant your seedlings. Here are the various Tomato Staking Techniques we have tried.

    - April, May, June
  • Tree Suckers and Waterspouts -

    In order to keep your trees producing and growing efficiently, promptly remove any suckers coming from the roots, branches growing from beneath the graft union, and rapidly growing vertical shoots from the branches (waterspouts).

    - June
  • Fertilizing Ornamentals During Drought -

    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 -

    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
  • Lawn Care -

    Be sure to water it as early in the morning as possible to avoid evaporation. This also helps reduce fungal diseases by giving the grass time to dry out during the day. Poor watering practices are the main reason for dead and dying areas in lawns and a common source of urban runoff.

    With shorter days in fall and winter, cooler temperatures, and a lower UV index, lawns will be less thirsty. Adjust the sprinklers monthly to water less as the winter rains kick in.

    When mowing, set the blade height as recommended for the type of lawn you have. Mow frequently enough so that only one-third of the leaf is removed at any one time. Dethatching the lawn with a special thatching rake is also a good idea. This removes dead material and allows water to reach the roots more easily. 

    Use the UC Guide to Healthy Lawns to learn more about mowing, irrigating, fertilizing, detaching and aerating. Better yet, take advantage of the County's Landscape Replacement Program!

    - May, June, July, August, September, October
  • Soil Solarization -

    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
  • Garlic Harvesting -

    If you can't smell the garlic from your home in the mornings like so many Valley residents can, then all you need to do is check the Gilroy Garlic Festival dates to know it's harvest time! I use the "stop watering Mother's Day, harvest on Father's Day" advice to remind myself, but anytime late June or early July you should start looking closely at your plants. Because it's an underground harvest, timing is more important; harvest too early and the shelf life diminishes; harvest too late and the garlic can be overripe. Generally, you'd like to see the lower leaves brown and some green still on the upper leaves. After digging up, put the garlic out of direct sunlight in a place with good air circulation. The University of California Vegetable Research Center has additional general Information on Garlic (including recommended varieties and problem diagnosis info). See UC Pest Note on Onions and Garlic for diseases and pests that affect garlic.

    When harvesting save the biggest bulbs of garlic. If you save the biggest of the bulbs, you can plant those cloves again next year increasing your odds for a great crop. The UC Master Gardeners of Napa County have more information about Growing Garlic.

    - June, July
  • Fresh Fruits and Vegetables Without a Garden! -

    If you like the freshest possible produce but don't have the space or time to grow your own, find a certified Farmers Market or a farm selling directly to consumers. The County of Santa Clara website has a Farmers Market page with links to certified Farmers Markets and the Country Crossroads map shows where you can buy more than 100 commodities directly the farm source.

    - June, July, August, September
  • Water the Roots, Not the Plants -

    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
  • Tomato Bottom Scarring -

    Tomato bottom scarring

    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
  • Container Color Choice -

    If you are growing plants in containers, keep in mind that light colors do a better job at reflecting the sun. This helps keep the soil from drying out too quickly and reduces the chances of the roots burning. If you already have dark pots, consider painting them a lighter color, or be especially careful about watering.

    - April, May, June, July
  • 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. 
    - June, 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
    - June, July, August
  • Basil -

    To extend your basil harvest, pinch the flowers off the tips as soon as they start to develop to prevent the plant from developing seeds. When selecting leaves for eating, choose young leaves at the top of the plant and cut the stem at that point. This will help the plant branch out as it produces new growth.

    - June, July
  • Eliminating Perennial Weeds -

    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

2. What to plant

  • Tomatillo (Physalis philadelphica) -

    TomatilloTomatillos still to this day is a truly wild plant. Attempts to hybridize them have failed. The plant is native to Mexico and was brought to the U.S. by Mexican Indian immigrants. It has a tart green apple taste and is the main ingredient in green salsas. It is also used in soups, stews, and guacamole.

    It is a member of the Solanaceae (nightshade) family as is the tomato and will grow any place a tomato will. It is fairly drought tolerant. Being a wild plant, there is a great deal of variability in plant habit, fruit size, etc. It is an annual, a low growing, sprawling plant usually not more than 2 feet high.

    The tomatillo has small, sticky, tomato-like fruits enclosed in papery husks. They are 1 to 3 inches in diameter and green or purplish in color. Culture is very similar to that for tomatoes or peppers. Plantings are generally direct seeded. The first harvest is ready in 70 - 80 days. They are not ripe until the fruit begins to break through the husk.

    - June, July
  • Attracting Bees -

    Bees are pollination workhorses, increasing garden production. Many plants will not produce fruit unless flowers are pollinated. Colorful annuals, such as Cosmos, edible African Blue Basil, and Salvias attract bees. You can also allow herbs and other plants to flower to create bee-friendly landscapes.

    The University of California at Davis has a garden dedicated to bees. The Honey Bee Haven website has more resources, including a list of plants they grow.

    - March, April, May, June, September, October
  • Nematode Control with Marigolds -

    Some varieties of marigold can suppress certain damaging nematodes while adding color to the garden. The Tagetes species suppress root knot and lesion nematodes. French marigolds, including Nemagold, Petite Blanc, Queen Sophia, and Tangerine, are most effective. Avoid signet marigolds, T. signata or tenuifolia, because nematodes will feed and reproduce on these. Marigolds don’t work well against the northern root knot nematode, Meloidogyne hapla, a species common in areas with cool winters. The effect of marigolds is greatest when grown as a solid planting for an entire season. When grown along with annual vegetables or beneath trees or vines (intercropping), nematode control usually isn’t very effective. To prevent marigold seed from getting in the soil, cut or mow the plants before the flowers open. As with other cultural control methods, nematode populations rapidly will increase as soon as susceptible crops are grown again. Learn more at the UC Pest Note on Nematodes.

    - June
  • Growing Peppers -

    As soon as average night time temperatures are above 55° F, peppers can be added to the garden. Before that time, they can be started indoors. Make pepper more productive by planting different varieties closely together. You will get more peppers per square foot because the plants support each other and provide protection from sunburn. Plus, they look lush and beautiful. After planting, it is a good idea to remove flowers and fruit from large-podded plants the first four to six weeks to encourage deeper roots and more foliage. Learn more pepper tips by consulting our Growing Great Peppers and Chiles page.

    - May, June
  • Milkweed -

    Milkweeds are the required host plants for monarch butterflies. Milkweeds provide food for the caterpillar, nectar for the butterfly, and chemical compounds that make the monarchs distasteful to predators. Make sure to choose a variety native to California. The non-native Tropical Milkweed may disrupt monarch migration patterns, because of it's longer growing season, so don't plant it unless you're willing to cut it back to 6" or less from Oct-Feb. Learn more at the UC ANR blog posting on Overwintering Monarchs.

    - May, June
  • Don't Plant an Invasive Plant -

    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. The California Invasive Plant Council (Cal-IPC) Don’t Plant a Pest! website will help you find alternatives to common invasive plants.
     
    - April, May, June, July, August, September
  • Plants to Attract Butterflies -

    Butterfly populations fluctuate in response to climate and habitat conditions. Many have specific host plants on which they feed and breed. Some common plants for attracting butterflies are milkweed, lantana, buddleia, and zinnias. For an extensive list of relationships between specific butterflies and host plants, see Art Shapiro's Butterfly Site at UC Davis.

    - March, April, May, June
  • Vegetable Planting Chart -
    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
  • Asian Vegetables -
    You can easily grow some vegetables used in different types of Asian cuisine and found in Asian markets. They are not necessarily native to Asia but have found their way into various cuisines. One way to decide which food to grow yourself is to choose varieties that aren't readily available or are more expensive in your local markets. It’s also fun to impress your family, friends, and neighbors with something they may not have seen growing before. Possibilities include sesame seeds, bitter melon, daikon radishes, gai choy, and opo. You can start cruciferous vegetables such as bok choy and Napa cabbage from seed now.
     
    More Information: Asian Vegetable Varieties
    - February, March, April, May, June, September, October

3. Pests and Diseases

  • Powdery Mildew -

    Powdery mildew on squash leaves

    Powdery mildew fungus is a common disease on many plants and produces a white powdery appearance on leaves and other plant parts. It can be found on roses, dahlias, chrysanthemums, peas, squash, and more. Some plants are so susceptible that you would be better off removing the plant.

    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 and sometimes on fruit. Eventually, the leaves will turn brown and dry.

    Some strategies for dealing with powdery mildew are planting resistant varieties, maintaining good air circulation, washing off the powder in the mornings, using sulfur sprays (careful with edibles), and removing affected parts.

    More Information about powdery mildew on: Fruits and Berries, Ornamentals, Vegetables
    - May, June, September, October
  • Codling Moth -

    "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 coddling 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 is a very labor intensive method. Heavy infestations may require the use of pesticides on the moths, before fruit is affected. For more information, refer to the UC Pest Note on Codling Moths.

    - May, June, July, August, September
  • Integrated Pest Management and Beneficial Insects -

    UC IPM LogoOur gardens contain far more beneficial insects than pests. Any time pesticides are used, both good and bad insects die. This upsets garden ecosystems. Use of pesticides can also pollute waterways and may put our children and pets at risk, along with other environmental consequences. We can dramatically reduce pest problems by practicing  Integrated Pest Management, which includes planting native species, following good cultural practices, and encouraging beneficial insects, such as lady beetles, lacewings and soldier beetles

    - April, May, June, July, August, September, October, Any month
  • 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. 
     
    - May, June, July, August
  • Snails and Slugs -

    Snails and slugs are patrolling your garden right now looking for new growth. Our preferred non-toxic method for dealing with them is to handpick early in the morning, or at night by flashlight. They can be saved for your friends with chickens, or crushed in place. If you do use snail bait, those made with iron phosphate are not toxic to pets and wildlife and they work well enough. For a full run-down of which management methods work, see the UC Pest Note on Snails and Slugs.

    - February, March, April, June, October
  • Weed Management -
    While some weeds are edible (purslane, nettles, dandelions), many are a nuisance and compete with your chosen plants for water and nutrients.

    Whichever variation of “One year’s seeds makes seven years’ weeds” you prefer, the truth remains: a key part of weed control is not letting them go to seed. For best results, work on removing weeds before they are able to propagate. Hand pulling and hoeing are effective methods for killing many common weeds.

    It’s less important to know the names of the weeds than to know how they spread. If they propagate by seed, pull or hoe them before they flower and go to seed. If they re-grow from roots, pull up as much of the root as possible. Only non-propagating parts are advisable to throw in the compost bin.

    Knowing what kind of weeds you have can be helpful in choosing the best management method - to learn more, see UC's Weed Gallery for help identifying weeds and the UC Pest Note on Weed Management in Landscapes for information about control.

    - February, March, April, May, June, July, August, Any month
  • Sudden Oak Death -

    Sudden oak death is a disease of oak trees caused by an invasive plant pathogen, Phytophthora ramorum. It occurs in Santa Clara County as shown on this map. If your oak tree went from healthy (green) to dead (brown) with a full complement of dead lives on the tree, it might have died from sudden oak death. More details about what to do are available at UC Pest Note on Sudden Oak Death.

    - June
  • Earwigs -

    Earwigs are third only to snails and slugs in causing plant damage. While they are beneficial because they eat insects such as aphids, they also feed on soft plants. Earwigs can do quite a lot of damage if there is a high population. They feed at night and hide in moist, tight-fitting places during the day. Trap them by putting out moistened, tightly rolled newspaper or corrugated cardboard in the evening. In the morning dispose of the paper and the trapped insects. Another method of control is a covered container such as a small margarine tub with holes cut halfway up the sides. Pour in about an inch of soy sauce and a thin layer of vegetable oil in the container and bury up to the holes. Empty as needed. Other control methods are described in the UC Pest Note on Earwigs.

    - May, June
  • Gophers -

    Our local gophers are also called pocket gophers. They make their presence known with crescent shaped mounds of dirt in the garden. Snacking on plant and tree roots as they tunnel through the soil, they are active year round and can have up to three litters each season in well-watered areas. Gophers also gnaw on irrigation lines and divert water into their tunnels, making it difficult to properly water plants. Adults live about three years. Homeowners can use several methods to control them. Locating the main tunnel is the first step. Placing Macabee or Gophinator or box traps or poison baits are explained in detail in the UC Pest Note on Gophers. Another method involves excluding them with wire fencing. Ultrasonic devices and chewing gum have been tested and are not considered to be effective.

    - May, June, July, Any month
  • Spotted Wing Drosophila -

    Unfortunately, the Spotted Wing Drosophila is infesting local cherry, berry, and some other fruits. Look for holes in the fruit. Once the eggs hatch, maggots develop and feed inside the fruit, causing the flesh of the fruit to turn brown and soft. Dispose of infested fruit. Information on identification and control can be found in the UC Pest Note on Spotted Wing Drosophila.

    - May, June
  • Squirrel Control -

    Squirrels can be particularly annoying because they tend to take one bite out of each piece of fruit, rather than eating the whole thing and leaving the other fruit intact. They are difficult to control, but you can try some of the methods recommended in UC Pest Note on Tree Squirrels and UC Pest Note on Ground Squirrels.

    - June, July, August, Any month
  • Verticillium Wilt -

    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
  • Ant Control -

    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
  • Whiteflies -

    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.

    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.

    - June, July, August, September
  • Armored Scale Control -

    These parasites suck the living sap from shrubs and trees. Armored scale insects are in the crawler stage in early summer (June). Armored scale has a hard stage that is very resistant to sprays. Control them during the crawler stage when they are soft and vulnerable. Spray with a horticultural (not dormant) oil, once a month for three months. See the UC Pest Note on Scales for important information about spraying.

    - June, Any month
  • Carpenter Bees -

    A carpenter bee visits a flower. (Photo by Kathy Keatley Garvey)Female carpenter bees are large, black and shiny. Male carpenter bees are similar in appearance to bumble bees. Both are about an inch long. Males do not sting and females sting only rarely. Carpenter bees are considered beneficial insects because they pollinate many plants and trees. For their nests, they tunnel into unpainted softwoods such as pine, fir and redwood in house or garden structures. Adults over winter in the nests, emerge in the spring, mate, deposit food in the tunnels and lay eggs. The tunnels are sealed with wood pulp and the new adults chew their way out. After the bees emerge, fill the holes with steel wool and wood filler. Apply paint to the surface to prevent re-entry. Further information is available in the UC Pest Note on Carpenter Bees.

    - May, June
  • Eugenia Psyllid -

    This psyllid has been a real problem in California. New leaves on the infected Eugenia look very much like peach leaf curl. The leaves also may become discolored. Thanks to the diligent work of the entomology researchers in biological insect control at UC Berkeley, a parasitic wasp called Tamarixia was released in Santa Clara County in 1993. The wasp is known to go as far as 45 miles and is found throughout the county. It is essential that no insecticide be used on Eugenia species. The Tamarixia wasp cannot do its job if it's poisoned. For more information see the UC Pest Note on Psyllids.

    - May, June
  • Tick Information -

    Ticks are abundant after mild winters and they can carry dangerous diseases. To learn more about ticks, see this Consumer Reports article on tick season or the UC Pest Note on Lyme Disease. Be sure to visit the County of Santa Clara website for information about ticks.

    - June
  • Fusarium Wilt -

    This is the most prevalent and damaging tomato disease. It also starts with the yellowing of lower leaves, but the yellowing may be only on one side (stopping at midrib) of the leaf or just one branch or one side of the plant. The older leaves will droop and curve downward. The yellow leaves wilt and die, gradually killing the whole plant. Sometimes a single shoot is killed before the rest of the plant shows any damage.  More information at UC Pest Note on Fusarium Wilt.

    - June, July
  • Fire Blight -

    Late spring and early summer are the time fire blight shows itself. Fire blight is a bacterial disease that makes plants look as though they have been damaged by fire. It attacks apples, pear and quince, most often, but can also infect ornamentals, such as toyon and pyracantha. Very often, the growing tip folds over into a shepherd’s crook shape.

    Fire blight spends the winter in cankers or wounds on the plant and resumes bacterial growth in the spring. There may be oozing from the canker. It is spread by insects, rain, or pruning. Infection can extend into limbs, trunks, or the root system and can kill the tree. Complete removal of any diseased tissue is critical. Dip clippers into a 1 part bleach, 9 parts water solution between each cut to prevent reinfection. The final cut should be 8-12 inches below the diseased area. The UC Pest Note on Fire Blight contains photos and more information.

    - April, May, June
  • Mosquitoes May Be Breeding In Your Yard -

    According to Santa Clara County Vector Control, many people are unaware they may be raising mosquitoes in their backyard, they offer mosquito tips including identifying possible breeding grounds. UC has created a Youtube video titled Don't Let Mosquitoes Breed in Your Yard.

    - May, June, July, August, September, October
  • Tomato Russet Mite -

    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

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