| Vegetable & Herb Gardening - August 2008
Please Note: All recommendations are for central Maryland. Time frames shift two weeks earlier in Southern Maryland and the Eastern Shore and two weeks later for Western Maryland. Check publications for further information.
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To avoid disease and insect problems on ripening tomatoes try harvesting them when they first change color and let them ripen indoors, unrefrigerated.
- Many vegetables need to be cured or dried and then stored under proper conditions. Onions should be harvested when tops die back. Let them dry in the garden after digging or tie the stems together and hang in a garage, attic or shed. When the neck is tight and the outer scales dry, trim the tops and roots within an inch or two of the bulb and store in a cool, dry location.
- Harvest your pumpkins and winter squashes when the rind hardens. Cut them from the vine leaving a 4-5 inch handle and store in a cool location until ready to use. This will probably happen prior to the first frost. Be careful not to nick or bruise the fruits and store them in a dry location at 50-55°F.
- Sweet potato roots will continue to enlarge until frost so check root size to determine when to harvest. Handle harvested roots gently and cure the roots by storing them at 85°F. and high humidity for 4-7 days. Thereafter, your sweet potatoes can be stored in a cool, dry location.
- Dig white storage potatoes on a cloudy, warm day after plants begin to die back. Let them lay on the ground for a few hours before bringing them inside. They should not be washed. Store potatoes in a dark, cool location (35°- 40°F.)
- Gourds should be allowed to dry on the vine and harvested prior to frost, leaving 2-3 inches of stem for a handle. Let them cure in a well-ventilated, cool dark location. Rub each gourd gently with rubbing alcohol or a weak bleach solution and don’t allow them to touch one another.
This is a good time to locate a source of garlic cloves and multiplier onions for planting in October and November. Purchase bulbs from a reputable seed company. Do not use store bought garlic for planting because of the significant risk of introducing white rot, a devastating fungal disease.
Plant cool season vegetable crops now that will mature into the fall months. These include broccoli, cauliflower, Chinese cabbage, turnips, kale, mustard, spinach, lettuce, carrots, and beets. Keep seedlings and transplants well watered and mulched. Spinach and lettuce seeds may germinate poorly in warm soils and should be sown heavily to compensate. When planting fall vegetables, be aware that more time will be required to bring the crop to maturity because of reduced light and ambient temperatures. Add at least 2 weeks to the “days to maturity” number on your seed packets. Plan to cover your newly planted garden crops with a floating row cover to protect them from pests and to extend the gardening season.
Cover crops of oats, winter rye, winter wheat and hairy vetch can be sown from late August through the middle of October. Seeds should be in close contact with soil to promote germination.
Sunflowers can be harvested when the backs of the flowers are dry. Cut the stalks one foot below the flower head, tie them together and hang upside down in a cool dry place.
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Insects and Mites
Mexican bean beetle larvae and adults are feeding heavily and continue to skeletonize bush and pole beans. The adults are coppery in color, resemble ladybird beetles and have 16 black dots on their wing covers. The larvae are yellow and fuzzy in appearance. You can handpick them or try a pyrethrum and soap insecticide; Neem products are also labeled for use on this pest. A very effective biological control is also available from the Maryland Department of Agriculture (MDA). They currently raise and sell the non-stinging parasitic wasp, Pediobius foveolatus. This tiny beneficial will seek out and parasitize Mexican bean beetle larvae. The wasps will not overwinter, but they do provide very good long-season control. Call MDA at (410) 841-5920 for more information and to order a supply of wasps.
Brown and green Southern stinkbugs are active on tomatoes and peppers. They feed on the fruits producing a yellow or white “cloudy spot” directly under the fruit skin. These spots become hard but can be cut out with a sharp knife and won’t affect flavor. If stinkbugs are a problem, try handpicking or spraying pyrethrum. The spray must contact the stinkbugs to be effective.
A second generation of squash vine borer adults is flying in Central Maryland. Monitor late crops for boring damage on stems. Well-watered squash plants that remain wilted are probably infested with the squash vine borer. Locate the borer by looking for mushy areas along the lower stem and signs of sawdust-like frass. Cut a vertical slit into the stem with a sharp knife, and locate and remove the borer. Mound up soil around the wound.
Harlequin bugs, cabbage aphids, cabbage flea beetles and several different caterpillars are all significant pests of members of the kale and broccoli family. Handpick, use a floating row cover to exclude them ,or be prepared to spray with a labeled insecticide.
Spider mite populations are high during hot, dry weather. Damage occurs on many vegetable plants. You’ll notice yellowing leaves that look dusty or dirty on the underside. Mites are pinpoint size sucking pests that can be observed on leaf undersides with the unaided eye. Keep plants hosed down during hot dry weather. Spraying insecticidal soap or horticultural oil on mite damaged plants during hot weather can cause serious leaf burn. If you notice spider mite damage on different types of plants in your yard you might consider purchasing and releasing beneficial mites that will hunt down and consume the pest mites.
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Disease
Sunscald may be a problem now on tomatoes, eggplant, peppers and melons. Fruits that are exposed to direct sunlight are prone to this disorder. Areas of the fruit skin become bleached out and soften making the fruits inedible. Fruits with blossom-end rot or sunscald should be pulled off immediately.
Peppers that are allowed to ripen will be subject to attack by the fungal diseases alternaria and anthracnose. No chemical controls are recommended. Picking some of your peppers while they are still green will encourage the plant to produce more fruit.
High heat can take a toll on home vegetable gardens. Excessive heating of fruit causes softening, uneven ripening, sunscald and color changes. High temperatures can prevent pepper, tomato and bean plants from forming fruits or pods. They should resume fruiting with a return to cooler weather. Hot weather may also cause lower tomato leaves to roll. Dieback of older leaves is natural, particularly when plants are stressed.
Defoliation of tomato plants is caused by fungal diseases like early blight and septoria leaf spot. These diseases start out early in the season as small leaf spots which enlarge and spread as the season progresses. Foliage loss often leads to reduced yields and sunburning of exposed fruits.
- If you have persistent problems with foliar diseases follow these steps next year:
Rotate your tomato crop to a new area of the garden.
Increase the spacing between plants.
- Cover the soil with a mulch to prevent the pathogen from splashing from the soil to the foliage.
Remove badly infected leaves during the growing season.
- As a last resort, spray a labeled fungicide, like fixed copper. Pull up and dispose of infected plants at the end of the season. Don’t compost these plants unless they can be shredded and hot composted.
Southern blight can affect tomatoes and peppers. The lower stem turns black and plants begin to wilt. Tan colored fungal fruiting bodies, the size of a small seed may be observed on affected stems. The only solution for this soil-borne fungal disease is to remove and dispose of the affected plants. Southern blight is a significant disease of thyme and other herbs and is encouraged by hot, humid weather.
Southern bacterial wilt usually causes wilting from the top of the plant downward. This disease is also known as Ralstonia and is brought into the garden by infected seed and transplants.
Fusarium wilt disease causes healthy plants, such as tomatoes, to begin wilting from the bottom up. Infected plant stems show brown discoloration of the vascular tissue. Remove and dispose of infected plants. This disease survives in soil for many years. Select cultivars with fusarium resistance.
Well-watered cucumber and muskmelon plants with wilted vines are probably suffering from bacterial wilt disease that is spread by cucumber beetle feeding. Remove infected plants and do a better job next time of controlling cucumber beetles.
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Herbs
This is a good time to divide overgrown perennial herbs and prune out damaged and dead plant parts. It is also a good time to propagate herbs by stem cuttings. When taking cuttings, snip off a 4-5 inch length of stem, remove all but the topmost leaves, and dip the bottom end in a rooting hormone and insert into a loose potting soil. Keep the cuttings moist until they become rooted, then transplant to larger containers.
Harvest the individual leaves of tarragon, rosemary, basil, sage and other culinary herbs and dry them indoors. Herb leaves are most intensely flavored right before the plant blooms. Snip foliage in the morning after the dew has dried. To dry down herbs for storage, tie the cut stems together and hang them upside down in a dry location. Cover with a paper bag to avoid losing the shattered leaves. Store dried herbs in glass jars away from light and heat. Fresh basil can also be frozen in plastic containers.
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Vegetable and Herb Gardening Tips - July 2008
Vegetable and Herb Gardening Tips - August 2008 |
