Gypsy moth caterpillars
Gypsy moth caterpillars denuding a small tree.

GARDENER’S CHECKLIST: Week of June 24, 2021

As spring becomes summer, Ron has advice on taking good care of your vegetable plants.

* Control gypsy moth caterpillars currently devouring the foliage of trees and shrubs by applying a biological pesticide containing Bacillus thurigiensis kurstaki (e.g. Monterey B.t.). This makes sense for caterpillar infested small trees and shrubs but not for large trees. That task would require spraying by a certified arborist.

* Hill up potatoes one more time. Many of the plants are now flowering, an indication that the potato tubers are forming. Though you’ll want to leave the plants intact and allow most of the tubers to reach full maturity later in summer, you can satisfy your potato craving by digging a few so-called new potatoes. Sift around in the soil mound around these flowering potato plants and pull out a couple of the tubers. These new potatoes have thin skins so there is no need to peel. Just boil them for about 25 minutes and eat.

Potato plants in early season
Hill up potatoes one more time and then allow the plants to develop their tubers. However, do on occasion dig into the mounds and pull out a few sweet tasting new potatoes for dinner.

* Avoid overhead irrigation of tomato plants. Overhead irrigation doesn’t mean holding the hose above your head. Rather, it applies to sprinkler systems or other watering methods in which water falls onto plants, wetting the leaf surfaces. Excessive wetting of the leaves promotes leaf diseases such as early blight. Apply water to the soil, e.g., by way of a drip irrigation system. Actually, this disease management strategy applies to the watering of any plant that is prone to leaf diseases.

* Spray the base of stems of summer and winter squash and that of melons with a biological pesticide containing Bacillus thuringiensis. This is to control squash vine borers, a common and destructive pest of vine crops. As an alternative, cover squash plants with a row cover to keep borer adults from laying their eggs on the stems of the squash. Adults of the borer are yellow and black moths that resemble wasps. Once squash begin to flower, remove the row covers to allow for pollination by bees. Sow seed for another crop of squash just in case the first crop succumbs to damage by the borers.

* Sow seed of Brussels sprouts, cauliflower, and late varieties of cabbage when space becomes available after harvesting pes and other early season crops. These will be ready for harvest in mid-autumn when there won’t be much else left in the garden.

* Refrigerate strawberries right after harvest if they won’t be eaten immediately. Place the berries in a colander over a large bowl with a damp towel at the bottom and seal the bowl and colander with plastic wrap. Don’t wash the fruit until ready to eat.

* Make one more harvest of asparagus and then allow the remaining spears to fully develop their fern-like growth. Do continue to keep an eye or two on the asparagus bed since asparagus beetles are common throughout the growing season and will feed on the plants. Such feeding weakens the plants and subsequently reduces future harvests. Hand pick the adult beetles and drop them in a container of soapy water.

Asparagus spears developing to maturity.
After one more harvest, leave the asparagus spears to develop to maturity.

* Prune spring blooming shrubs that have completed their flowering. Cut back wayward branches; otherwise prune just to shape the plants and to remove dead, diseased or damaged branches. Avoid hard pruning, i.e. removing more than ten percent of the growth.

* Begin treating phlox, beebalm, lilac, and other plants susceptible to powdery mildew with a fungicide. Warm, humid conditions favor development of powdery mildew. Applying a fungicide containing sodium bicarbonate (baking soda) or potassium bicarbonate is a safe way to control this plant disease. Another option is to apply an organic product called Serenade. While you’re at it, spray vine crops as well.

* Don’t assume that wilting plants growing in containers need additional watering. When it gets as hot as it did at times this past spring, many plants will wilt in response to the heat. Check soil moisture before applying water. Too much water can cause root rot.