Potato Leafhoppers

Potato leafhoppers (PLH) primarily impact potatoes, beans, and eggplant, but they are not picky eaters and have a wide host range, including other legumes (clover, soybean, alfalfa), solanaceous (tomato, pepper), and other vegetables (lettuce, celery). The presence of nymphs indicates an established population. Signs of injury begin with leaf veins turning pale, followed by the yellowing or browning of areas of the leaf or leaf tips which is known as "hopperburn". Leaves become brown, curl up, and die. Plants may be stunted and yields reduced or lost. PLH can also be a vector of many viruses.

Scout using sweep nets or by shaking plants to see if adults fly up when the plant is disturbed. Nymphs can be counted on the underside of leaves. Seedling beans should be treated if they have 2 adults per foot of row. From 3rd trifoliate leaf to bud stage, treat when PLH exceed 1 nymph per leaflet or 5 adults per foot of row. Repeat application in 7 to 10 days if necessary. In potatoes, treat if more than 1 adult per sweep is found, or more than 15 nymphs are found per 50 leaves. Be sure to treat lower leaf surfaces when spraying. In fields where systemic seed treatment was used, foliar treatment should not be needed before bloom.

See the New England Vegetable Management Guide for recommendations on insect control options for beans, potatoes, or eggplant. Additional information on management strategies can be found on the page for “Insects That Can Be Controlled By Row Covers”.

European Corn Borer (ECB)

Corn with newly emerging tassels should be scouted weekly for the presence of European Corn Borer (ECB) larvae. Inspect the tassels of 50 to 100 plants, in groups of 5 to 20 plants, throughout the field. Treat if more than 15% of the plants have one or more larvae present. Use of selective products to control ECB will conserve natural enemies of aphids and ECB.

An important note about ECB is that it has more than 200 host plants, from common weeds to cash crops. In addition to impacting corn, ECB can also be a significant pest for pepper growers, for example. In southern New England, there are two generations each year. The first flight occurs in June, with larvae present between late June and early July, and the second flight typically spans mid- July to mid- August.

Pheromone traps and action thresholds are the best way to monitor ECB moth flights. If trapping, it is necessary to use two traps with one baited with the Iowa or Z lure and the other with the New York or E pheromone blend. They should be placed with the opening at plant height, in the weeds bordering corn or pepper fields. Plan to empty the traps and count the moths every three to four days during the height of the season.

Reference Documents:

Sweet Corn Pest ID & Trapping Factsheet.pdf

Sweet Corn Pest Identification

See the New England Vegetable Management Guide for more details on management strategies for sweet corn insect pests.

Onion Thrips

Onion thrips favor hot, dry weather. As temperatures rise, we expect their numbers to rise rapidly too.

Adults overwinter in crop remnants, alfalfa, wheat, greenhouses, and weeds along the border of crop fields. They lay eggs one at a time in the plant epidermis, nymphs feed on leaves, and pupation occurs in the soil. Scout plants along field margins where infestations build early. Look closely between leaf blades to find the light-yellow nymphs or darker adults.

Damage may appear as silver lines, white patches, tip dieback, curling and twisting of leaves, slowed growth, reduced bulb size and yields, or if severe enough, can result in plant death. Begin applications when damage is first noticed or when there are 3 or more thrips per leaf.

The most effective material for organic growers is spinosad (e.g. Entrust) applied with insecticidal soap (e.g. M-Pede) to increase efficacy. Entrust can be used two times in a row before rotating to a different insecticide class. Neem oil (e.g. Trilogy) and azadirachtin (e.g. Azatin O) may be effective also if applied when poplations are still low. Pyrethrin (e.g. Pyganic) can provide knockdown control.

See the New England Vegetable Management Guide for more spray options.

Continue to be on the lookout

The following pests that were covered in the previous pest alerts and are still relevant in current conditions:

• Flea Beetles
• Cabbage Root Maggots
• Thrips
• Mites