Vegetables
Aphid numbers are still high now on a wide variety of landscape and garden plants. It is usually not necessary to spray insecticides or release beneficials to control aphids. Populations of lady bird beetle, green lacewings and wasp parasites build up quickly to keep aphids in check. You’ll see these predators and parasites at work if you observe the aphid colonies closely. Planting a wide variety of flowering plants that bloom throughout spring and summer will help attract and keep beneficial insects in your landscape. If necessary, an application of insecticidal soap or ultra fine horticultural oil will kill these soft bodied pests.
Cucumber beetles are either yellow with 11 black dots or yellow with 3 black stripes. They have a wide host range and begin to feed on all plant parts of all members of the cucumber family as soon as plants emerge. These pests transmit bacterial wilt disease, which causes mature cucumber and muskmelon plants to wilt and die. Controlling this pest early in the season is very important. Row covers can be used to cover plants to deter cucumber beetles or you can apply a labeled insecticide. Remove row covers when cucurbit family plants begin to bloom. ‘County Fair’ is the only cultivar with resistance to bacterial wilt disease.
Imported cabbageworm is active on mustard family members like broccoli and cabbage. They are small, cream colored caterpillars that become velvety green when fully grown. They chew large irregular holes in leaves and leave black droppings. Handpick them or spray with a B.t. product when larvae are small. Groundhogs prefer brassicas and peas and will chew these plants down to the main stems.
Handpick Colorado potato beetles and their orange egg masses on eggplant and potato plants. The B.t. product, “M-Trak” can be sprayed when larvae are small. A floating row cover also works well to exclude flea beetles and Colorado potato beetles.
The adults, larvae and eggs of Mexican bean beetle can be handpicked. The adults are coppery with 16 black dots and resemble ladybird beetles. Carefully inspect the upper and lower leaves of your plants for these pests and their egg masses.
Squash vine borer adults are laying eggs on squash and pumpkin stems. Monitor plants for signs of wilting and entrance holes on lower stems. You may see sawdust-like frass around the hole. Stems may contain more than one larva. They can feed inside the stems for up to 2 weeks. Here’s the easiest and surest method of control: cut a slit above the hole with a razor, remove the 1 inch long white larva with a brown head, and mound up soil around the wound.
Young tomato plants may be exhibiting symptoms of various leaf spot diseases such as gray leaf spot, septoria and early blight. Remove badly infected lower leaves, keep a thick organic mulch around plants and avoid overhead watering. Applications of tri-basic copper will slow down severe infections. Be sure to offer proper support to growing tomato plants. Pepper and eggplant also benefit from being supported by a low trellis or wire cage. The suckers or succulent shoots that develop from the tomato plants at the soil line should be removed throughout the season. You can plant these suckers for a late crop.
Swiss chard, Malabar spinach, and sweet potato leaves are good heat tolerant salad greens for Maryland. ‘Grand Rapids’, ‘Red Sails’, ‘Deer Tongue’, ‘Slobolt’, ‘Bronze Arrowhead’ and all oak-leaf type lettuces are some of the heat tolerant looseleaf lettuce varieties that can be sown now. ‘Jericho’ is a relatively new heat-tolerant romaine type of lettuce. All lettuce plants will grow better from now through August in a cool, moist, shady location.
Control weeds in the vegetable garden by laying down sections of newspaper covered with straw.
Young tomato plants may be exhibiting symptoms of various leaf spot diseases such as gray leaf spot, septoria and early blight. Remove badly infected lower leaves, keep a thick organic mulch around plants and avoid overhead watering. Applications of tri-basic copper will slow down severe infections. Be sure to offer proper support to growing tomato plants. Pepper and eggplant also benefit from being supported by a low trellis or wire cage. The suckers or succulent shoots that develop from the tomato plants at the soil line should be removed throughout the season. You can plant these suckers for a late crop.
Herbs
Cut back herbs through the summer to keep plants bushy and productive. Essential oils are most concentrated right before bloom. If you had trouble with southern blight on herbs in past years consider creating a raised bed. The improved water drainage will reduce the incidence of soil borne diseases.
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