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

September 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

  • Watering Trees -

    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 -

    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
  • 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
  • Winter Squash Harvesting -

    Winter squash is ready to pick when the stem begins to shrivel. Press the rind with your fingernail, it should resist denting. Pick before the first hard frost and cure by letting it lie in the sun for at least 3 days, turning it each day. Store in a cool, dry place. It will keep for up to 5 months.

    - September
  • Watering Trees -
    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
  • Yellowing Leaves on Gardenias -

    Chlorosis is usually caused by a lack of iron in the soil. With a mild case, the veins remain green and as it becomes more severe will turn completely yellow. Treat the soil with iron chelate according the package directions.

    - September
  • 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
  • Prioritizing Plants for Watering -

    Water is always a precious resource in California. It makes sense to think about which plants in your landscape will receive the limited water. California Natives and other drought tolerant plants can go long periods without water. Mature trees have deeper roots to find water, but can become hazards if they get too dry and start to drop limbs. Annuals and easily-replaced plants would be the lowest priority. Your Landscape During Drought has more information.

    - July, August, 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
  • Garden Sanitation -

    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. If pests are given a nice place to spend the winter, their populations are likely to be much higher next year.

    - July, August, September, Any month
  • 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
  • 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
  • How to Tell if Fruits and Vegetables Are Ready to Pick -

    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 -

    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! -

    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
  • Prune Apricot and Cherry Trees -

    There are several ways to squeeze multiple fruits into a small yard. You can graft related fruits onto the same tree, so that one tree might have apricots and plums and peaches or another might have four varieties of apples. You can choose dwarf trees or trees on dwarfing rootstock. You can plant them in larger containers like half wine barrels. You can plant them close together and keep them pruned small. And you can do summer pruning after harvest in addition to dormant pruning in the winter on most trees. Just make sure to do your annual pruning of apricot and cherry trees now so that they have time to heal before it rains again. See Eutypa Dieback on Apricot Trees and Cherry Trees under 3. Pests and diseases. The UC Home Orchard website has more advice on Pruning Apricots.

    - August, September
  • Keep Watering Until the Cool Weather Arrives -

    September is still a warm month in Santa Clara County. Continue watering established trees and shrubs until temperatures cool down. As a rule of thumb, trees should have a couple of deep waterings during the summer, if you haven't done that, now is a good time. Use a soaker hose or drip hose around the drip line of the tree and slowly water for two to three hours. Mature fruit trees need a bit more, fill the surrounding basin every 3-4 weeks, young fruit trees need water every couple of weeks.

    - September
  • Pinch Tomato Blossoms -

    Tomato blossoms (Photo: Felagund commons.wikimedia.org)In September pinch new blossoms off tomato plants to direct the plant's energy into growing and ripening already formed tomatoes. It takes several weeks to go from blossom to fruit, so the tiny little yellow flowers that are just starting now are unlikely to have time to produce good quality tomatoes.

    - September
  • Free the Trees -

    As your young trees grow bigger and stronger, remove supporting stakes or loosen the straps as early as possible. Some movement of the tree is important to make it healthier in the long run. If the tree is able to stand on its own, it will develop a thicker trunk with a taper at the bottom.

    - September, Any month
  • Oleander -
    These plants are obviously not terribly picky about conditions if they live and thrive in freeway medians. Oleander is drought tolerant once established. They rarely, if ever, need to be fertilized in our local soils or sprayed or pruned. But if you want to prune them to fit into a small yard space or to make them look like a tree rather than a bush, you can do so now. As with all pruning, first cut out any dead or dying branches. Then cut any that are deformed or growing in an undesirable direction. After that, you can prune for size and shape. Cut the plant back to a little smaller than the size you ultimately want, keeping in mind that it will re-grow. Take care not to prune off more than one-third of the plant at a time. Make cuts above nodes that face out in the direction in which you want new growth to go. All parts of the plant are poisonous so do not eat it, burn it, or work on it without gloves. The good news is that this latter quality makes it deer resistant.
     
    More Information: Oleander characteristics
     
    - September

2. What to plant

  • Ornamental Shrubs and Trees -
    Spring is when thoughts turn to planting, yet fall is an excellent time to plant perennials. You can plant many trees, shrubs, and other long-lasting plants in fall. This applies particularly well to California native plants. Putting them in now will give them a chance to start developing strong root systems with the winter rains before they are stressed by summer heat. Developing a healthy root system early in the life of a plant is important for long-term success.
     
    When choosing plants, consider our general Mediterranean climate as well as the microclimate of your yard. Sun times, water needs, wind exposure, and soil type can all impact the success of a plant. Make sure you know how large the plant will become, even if it looks fine now in a one-gallon or five-gallon container.
     
    More Information: Tree Selection Guide
    - September, October, November
  • 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
  • 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
  • When to Plant Cool-season Vegetables -

    In Santa Clara County, cool-season vegetables such as beets, Cool season leafy vegetablesradishes, peas, arugula, bok choy, chard, collard, lettuce, mustard greens, broccoli, cabbage, and spinach, can be planted in very early spring for early summer and harvested before they bolt (go to seed), or in late summer for harvest in winter. Use our Vegetable Planting Chart as a planting guideline.

    Cool-season vegetables grow well in temperatures ranging from 55°F to 75°F. Take a good look at your garden to determine the best areas for planting, remembering that cool-season vegetables need 6-8 hours daily of sun. 

     

    - February, March, April, September, October
  • Tree help -

    The city of San Jose has multiple resources for the home gardener. See their webpage on tree care. Oak trees (valley, live, blue), big leaf maples, and buckeyes are great choices for our region.
    SelecTree: A Tree Selection Guide from CalPoly can help with selecting the right tree for the right place in your landscape.     
    Apply for stewardship of one or more trees for 3-5 years at Our City Forest.

    - September, 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
  • Carrot Culture -

    carrotsIf you have a light fluffy soil, perhaps in a raised bed, you can grow those long beautiful carrots you see in the grocery store. However most of us have a heavy clay soil and it is best to grow the shorter varieties. Adding organic material such as compost rather than manure is good. The seeds are very tiny and mixing sand with them will help you not over-seed. Plant no more than 1/2 inch deep. Carrots are slow to germinate and could take as long as 3 weeks. Keep the soil moist until they're up. Thin to 2 or 3 inches apart. Plant every few weeks for a continuous crop. If you have limited space, try growing in among your ornamentals, their feathery tops can look quite pretty. They can also be grown in a container. Some common problems are twisted roots from planting too close together, forked or deformed roots from clods and rocks in the soil, hairy root from too much nitrogen and splitting from too much water.

    - September

3. Pests and Diseases

  • Leafcutter Bees - a Beneficial Insect -

    leaf damaged by leafcutter beeDo your rose bush leaves have smooth round holes in them? The likely culprit is the female leafcutter bee. The bee cuts smooth round or oval leaf fragments and uses them to line each underground brood cell that she fills with nectar and pollen. When the cell is ready, a single egg is sealed inside. The larva pupates (matures) in the chamber and emerges in the spring.

    Rose leaves seem to be their favorite. The hole in the leaf is much larger than an ordinary caterpillar would make and is very smooth as if a miniature cookie cutter was used. The bee can chew off a leaf fragment in less then a minute with its sharp jaws.

    Like all bees, leafcutter bees are important pollinators and should not be killed.

    - September
  • Spider Mites -

    Spider mites are closely related to spiders and are about the size of the period on this sentence. They feed on many kinds of plants. They suck out plant juices from leaves, flowers and the blossom end of fruit. Plant leaves may become stippled with yellow and webs may be visible. Hotter temperatures and dusty conditions encourage them. Conserving natural enemies by not using pesticides, providing sufficient irrigation and reducing dust may all help control mites. Periodic washing of leaves with water can be very effective in reducing their numbers. If treatment is necessary, spider mites can be controlled with insecticidal soap, horticultural oil or neem oil. Releases of predatory mites have been used in some situations. More information is available in the UC Pest Note on Spider Mites.

    - July, September
  • 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
  • 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
     
    - August, September
  • Eutypa Dieback on Apricot Trees and Cherry Trees -

    The sudden dieback of individual branches during mid to late summer can lead to dry brown leaves that may remain on the branches until the following winter. This is due to a fungal parasite caused by airborne spores that enter fresh pruning wounds. Cankers develop around an infected wound and eventually kill the branch. Death can take months or even years. The danger of spreading is highest in the fall during early rains and again in the spring. Prune apricot trees and cherry trees in July or August before fall rains begin. Apricot and cherry trees should be pruned at least 6 weeks before the first rain falls. If it rains before the pruning cuts heal, the tree is more susceptible to infection by Eutypa spores that cause dieback. See UC Pest Note on Eutypa Dieback

    - 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
  • Mosaic Virus -

    Mosaic virus on squash and cucumber plants is a disease spread by aphids and cucumber beetles. The leaves become rough and mottled, the plant becomes stunted and the fruit can be whitish. Pull the plant and put it in the trash. Do not compost. For more information see UC Pest Note on Squash Mosaic Virus.

    - September
  • Neem Oil -

    Neem oil is an approved pesticide in California for use on ornamental and food plants. It is derived from the neem tree. Aphids, caterpillars, loopers, mealy bugs, thrips, whiteflies, and diseases like mildew and rust are effectively controlled. It is most effective when alternated with insecticidal soap or pyrethrum, killing problem insects in different stages of development. Follow label instructions. Spray 2 or 3 times from 7 to 10 days apart. As with all horticultural oils, do not spray if daytime temperatures will exceed 90°F.

    - September
  • Rats -

    Have you found snail empty shells stashed in out of the way places, hollowed out Navel oranges, Meyer lemons with no skins, tomatoes with bite marks, fruit with holes gnawed in them or grape skins or cherry tomato skins scattered around? This could indicate the presence of rats. The UC IPM Pest Note on Rats provides a wealth of scientific information.

    Rats show up when your citrus, tomato or fruit first start to ripen. Rats are agile climbers and usually live and nest in shrubs, trees, and dense ground cover like ivy. 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.

    Trapping is the safest and easiest method for controlling rats. The simple snap trap is effective. The most important thing about trapping rats is to have lots of patience and keep trying. Wet some oatmeal enough for it to hold together, add dog or cat kibble or bits of lightly cooked bacon mixed in. Tie a walnut to the trigger and add a dab of peanut butter.

    Other baits to try are peanut butter and fresh fruit, but try to have something tied to the trigger. Set traps where rats are likely to travel or where you see droppings along fence lines or buildings. Bait the trap but do not set it for several days. Try different baits in multiple traps until you find one the rats like. Put two traps facing each other. After the rats are accustomed to being fed, then set the traps. If the rat springs the trap but doesn't get caught, move the traps to a different place and change to different baits. Rats prefer secluded spots and will be less wary there. Be sure to secure the trap with a wire or nails. Above all be patient and use multiple traps.

    - March, April, July, August, September, Any month
  • 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
  • Birds -

    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
  • Sooty Mold -

    Aphids, scale, mealybug and whitefly all excrete sticky honeydew that is colonized by sooty mold fungi. 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. A strong stream of water will wash the mold off leaves. The mold can be washed off fruit with mild soap and water. See UC Pest Note on Sooty Mold for more information.

    Ants protect the sucking insects from their predators in order to 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.

    Trim tree limbs touching buildings, fences or other access points as well. Baits such as ant stakes placed under trees and shrubs may help reduce ant foraging in some cases.

    For ant information, see the UC IPM Pest Note on Ants.

    - August, September, October, November
  • Brown Marmorated Stink Bug -

    Native to Eastern Asia, this pest was introduced to the United States in the 1990's and has been found in Santa Clara County. Described as “one of the worst invasive pests we’ve ever had in California” by UC Cooperative Extension advisor Chuck Ingels, this insect affects many different crops and is a serious residential problem. There's more information in the UC Pest Note on Brown Marmorated Stink Bug. View a map showing the distribution of the BMSB in California.

    Adult (top) and mature nymph of the brown marmorated sting bug
    Adult (top) and mature nymph of the brown marmorated sting bug

    - August, September
  • Bitter Pit (Brown Spots) on Apples -

    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 -

    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
  • Tomato blossom end rot -

    Tomato blossom end rotA brown depression on the bottom of tomatoes is usually blossom end rot. 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.

    - July, August, September
  • 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

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