July to-do list for gardeners:
Tackle tomato problems
1. Blossom-end rot is a very common problem that appears as dark, leathery patches on the bottom end of the fruit. It is generally caused by inconsistent watering and/or calcium deficiency. Try to water regularly, especially during hot, dry weather. Mulching around plants will also help prevent moisture loss. When planting new tomatoes, adding agricultural lime or calcium-based fertilizers will help prevent calcium deficiency.
2. Tomato russet mites deplete the juice from the cells of leaves, stems and fruit. They usually start at the base of the plant and move upward and, if not controlled, can kill the plants. At the first sign of damage, treat with sulfur dust or a spray solution of wettable sulfur and spreader-sticker. For details, go to: www.ipm.ucdavis.edu/PMG/r783400111.html.
3. Fusarium wilt is a serious fungus that invades the plant through its roots. Individual branches and leaves will become yellow and wilt. Infected plants usually die. To avoid this problem, plant resistant varieties, labeled (F), and don't plant tomatoes in affected soil for several years.
4. Verticillium wilt causes yellowing of older leaves. Leaves will develop a V-shaped pattern that turns from yellow to brown, and they will eventually die. Sun-related fruit damage occurs due to loss of foliage. Verticillium wilt seldom kills the plant, but it reduces vigor and yield. Rotating crops will help reduce the symptoms. Next year, plant varieties with (V) or (VF) designation, which are resistant to the wilt.
5. The tomato hornworm has eight chevron-shaped stripes on each side of its body versus the tobacco hornworm, which has seven diagonal strips. Hornworms can be extremely large, up to 4 inches long, and leave large, visible black droppings on the leaves. They feed on blossoms, leaves and fruit. They can cause extensive damage to the plant and scar the fruit. Handpicking is the best option for control. If necessary, spray with Bacillus thuringiensis (BT).
6. Check water levels of your plants by using a moisture meter or digging into the soil a few inches to ensure that the roots have sufficient water. Whether you are using drip irrigation, sprinklers or hand-watering, it is important to make sure you aren't over- or underwatering. Moisture meters can be purchased at most garden center or hardware stores for under $10.
7. Cucumber beetles feed on zucchini, crookneck squash, melons and beans. They can be difficult to control; handpicking is recommended. Adults overwinter in weedy areas, so it's best to control weeds year round.
What to plant now
Transplants: arugula, beets, beans, beets, Brussels sprouts, cauliflower, lettuce, summer squash.
Seeds: arugula, beets, broccoli, Brussels sprouts, corn, summer squash.
Have a question for Rebecca Jepsen or the other Santa Clara County Master Gardeners? Call the hotline, 408-282-3105, from 9:30 a.m. to 12:30 p.m. on weekdays or check www.mastergardeners.org.