By Rebecca Jepsen
for the Mercury News
July 4, 2009
Check water levels. With the recent heat, it is important to make sure you are not over- or under-watering. Use a moisture meter to check that the plant's root level has sufficient water.
Remove suckers from roses. Suckers are rapid-growing, long canes that should be easy to spot. Prune them below the bud union. Also deadhead roses, and apply an organic rose food. It is also a good idea to occasionally wash off roses using a blast of water from the hose. This will help remove aphids, ants and mites.
Handpick cucumber beetles. They feed on zucchini, crookneck squash, melons and beans. They can be difficult to control, which is why handpicking is recommended. Adults overwinter in weedy areas, so it's best to control weeds year round.
Common tomato problems
- 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. If not controlled, pests can kill plants. At first sign of damage, treat with sulfur dust or a spray solution of wettable sulfur and spreader-sticker. For details, go to the UC IPM Pest Note on tomato russet mite.
- 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). Rotate crops, and don't plant tomatoes in affected soil for several years.
- Verticillium wilt causes yellowing of older leaves. Leaves will develop a V-shaped pattern that turns from yellow to brown; they eventually die. Sun-related fruit damage occurs due to loss of foliage. Verticillium wilt seldom kills the plant, but 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.
- Tomato hornworm has eight chevron-shaped stripes on each side of its body vs. the tobacco hornworm, which has seven diagonal strips. Hornworms can be large, up to 4 inches in length, 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).
For a complete list of July gardening tips, click on www.mastergardeners.org/tips/july.html.
What to plant now
Transplants: arugula, beets, beans, beets, lettuce and summer squash. Local nurseries should have a good supply of most of these.
Seeds: arugula, beets, corn and summer squash.
To find a list of warm-season vegetables that do well in Santa Clara County, go to www.mastergardeners.org/picks/warm.html or call the hot line at 408.282.3105.