40th anniversary logo for 2020
August Tips & Events for Santa Clara County
“When gardeners garden, it is not just plants that grow, but the gardeners themselves .
~Ken Druse
Stink Bugs
If you see white or yellow dots on your tomato, they may be the work of a stink bug. These bugs are usually brown or green, about a quarter- to half-inch long, with a distinctive shield shape. You can find them by examining the plant, looking under the leaves, or shaking the plant until they fall off and can be identified. Also look for groupings of small white eggs on the leaves. The bugs and eggs can be handpicked (with gloves) and crushed or dropped into soapy water. Row covers can exclude them from susceptible plants. Several beneficial insects, like parasitic wasps and assassin bugs, can help control them naturally. Some of the stink bugs found in this area are the consperse stink bug , the southern green stink bug , and the bagrada bug . The brown marmorated stink bug is a recent local addition to this family and it can cause damage to many different fruits and vegetables. It can even get inside the house where it should be promptly swept or vacuumed up. Keep in mind that they are called STINK bugs for a reason.

More Information: Stink Bugs

Photo: Exotic and native adult stink bugs (size not to scale) from California, from California Agriculture website , by Mike Lewis
Sunscald on tomatoes
If plants did not develop a lot of leaf cover, perhaps due to a shortage of nitrogen, the “fruit” can get sunburned. The side facing the sun can take on a bleached look or turn light brown and leathery. This is purely an abiotic issue, meaning that it doesn’t result from a living organism like a disease or pest. The official name for this is sunscald. It can affect tomatoes, bell peppers, chiles with a thick flesh, or any number of fruits and vegetables. Plants need sufficient nutrients to be able to grow enough foliage so that their fruit has some protection from unrelenting sun, so keep fertilizing and watering the plants. In the meantime, you can use shade cloth, row cover, or other material to block a little of the sun from getting through. Keep in mind that most summer vegetable plants need six to eight hours of full sun for photosynthesis. Only the edible part may need a little protection from the strong sun.

More Information: Sunscald

Photo: Sunscald on tomatoes, by Laura Monczynski
Summer pruning of fruit trees
Fruit Tree Care
In the middle of a long hot summer it may be time to consider deep watering your established fruit trees. Younger trees just getting started need frequent watering, yet it is easy to forget about the mature trees that need no irrigation for most of the year. Many fruit trees will benefit from deep watering once a month during the dry months. Our clay soil absorbs water slowly and holds onto it for a long time, so water slowly to allow for deep penetration.

This is also the best month to prune apricot and cherry trees so that the pruning cuts will close before rains come and splash around disease spores. Other fruit trees can be pruned right after completing their harvests. Pruning in the summer as well as during the dormant season helps keep backyard trees to a manageable and pickable size.

Keep harvesting ripe fruit and promptly picking it up from the ground. Leaving rotting fruit will attract pests and allow disease organisms to grow. And you are growing the fruit to eat, right?

Photo: Summer pruning of fruit trees, University of California
Anecdotally at least, it seems that this has been a good year for hummingbirds. Perhaps they are happier because the world is quieter. Or perhaps people are spending more time in their gardens and observing more of nature. The tiny birds can be seen darting from plant to plant and can dive at speeds of up to 60 mph. You might even be lucky enough to follow them with your eyes and find their nests. With long proboscises, they frequent flowers with tubular shapes. They can be attracted with a hummingbird feeder if it is kept clean, although nature has successfully been supporting hummingbirds for twenty-two million years. The best thing you can do for the hummingbirds is to plant flowers that attract them and provide them with the food and nutrients they need. They, in turn, will provide you with well-pollinated plants and hours of peaceful entertainment.

More Information: Hummingbird Health

Photo: Anna’s Hummingbird on its nest at Prusch Park, by Allen Buchinski
How do you know if that caterpillar in your garden is going to turn into a beautiful butterfly or a fascinating-looking moth? How do you decide whether to leave it or remove it? How much damage can and should you tolerate on your plants for the greater good? A caterpillar is the larval stage of a moth or butterfly, yet it isn’t always easy to know into which it will metamorphosize. There are many caterpillar identification guides online to assist you. If the caterpillars are damaging your fruit or boring into trees, they need to be removed. Options are handpicking, allowing natural predators to do the work, or spraying with a product containing Bacillus thuringiensis (Bt). If you see caterpillars but no obvious damage, you can research them to learn if they could cause damage and to decide how much you are able to tolerate. Planting known larval hosts for butterflies will help attract the types of caterpillars that will become beautiful butterflies. And if the purpose of the plant is to support the butterflies, you won’t mind if the caterpillar eats a lot of that plant.

More Information: Caterpillars

 Photo: Monarch caterpillars on milkweed, by Kathy Keatley Garvey
Upcoming Events
We're still mostly offering online events, but we've scheduled two open-garden-days in Palo Alto this month. We hope to see some of you there! Keep an eye on our events page for the latest schedule.

Sat, Aug 08, 10:00 a.m.–12:00 p.m., Palo Alto Demonstration Garden Open Again! , Eleanor Pardee Park, 851 Center Drive, Palo Alto

Wed, Aug 12, 7:00 p.m.–8:00 p.m.,  ONLINE Gardening in Late Summer

Sat, Aug 15, 7:00 p.m.–8:30 p.m.,  ONLINE Vertebrate Pest Management for your Yard and Garden  

Sat, Aug 22, 10:00 a.m.–12:00 p.m., Palo Alto Demonstration Garden Open Again! , Eleanor Pardee Park, 851 Center Drive, Palo Alto

Wed, Aug 26, 4:00 p.m.–5:30 p.m.,  ONLINE Sustainable Landscaping Fundamentals

Visit the UC Master Gardener Program website  for additional information including an up-to-date list of events and classes .

Have a gardening question? Contact our Help Desk (for Santa Clara County residents). Start by reviewing our plant  problem diagnosis tips .
  • Mon-Fri 9:30 a.m.–12:30 p.m., 408-282-3105
  • Fri ONLY 1:00 p.m.–4:00 p.m., 650-329-1356 (Closed Dec. & Jan.)
  • Or send us your question online

The University of California Cooperative Extension (UCCE) Santa Clara County Master Gardener Program volunteers are trained under the auspices of the UCCE. Our mission is to promote sustainable gardening practices by providing up-to-date, research-based horticultural information to home gardeners.

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