Worms

IPM Threshold Guide for Agronomic Field Crops

This general term applies to the larvae (caterpillars) of a large number of butterfly/moth species (Lepidoptera) in the noctuid family that feed on buds, young shoots and leaves. Cutworm damage most commonly occurs in vineyards with weeds under the trellis or mulch, and in sandy or light colored soils.

Although fall armyworm (Spodoptera frugiperda) is a native pest to North America and a chronic pest in the southeastern US, reports of fall armyworm activity and outbreaks are unusually high this year. There are numerous reports of heavy fall armyworm activity coming out of Virginia, Kentucky, Indiana, Illinois, Ohio, and other states. In Maryland, there have been cases reported across much of the state so far, including Anne Arundel, Baltimore, Charles, Calvert, Frederick, Howard, Montgomery, Prince George’s, St. Mary’s, and Washington counties. Weather conditions have allowed fall armyworm to flourish this year, so producers are encouraged to be on the lookout for potential problems.

On a recent visit to a farm I saw bright yellow leaves in a pumpkin field and wondered if this could be Cucurbit yellow vine decline that was first seen two years ago (fig. 1). Upon closer inspection of the plants it was found to be an old nemesis of pumpkins and squash - the squash vine borer. Borer moths lay eggs mostly at the base of pumpkin and squash plants starting in late June and going through the first few weeks of July. Eggs hatch and borers quickly move their way into the base of the pumpkin stem where they feed inside the stem (fig. 2) disrupting water and nutrient flow to the rest of the plant (fig. 3).

Although sorghum faces relatively few pests compared to our other grain crops, it is not a “plant and forget” crop. Sorghum is often grown on marginal ground, in areas with greater deer pressure, dryland fields, and as a rotational component for managing weed and disease pressure. Sorghum is generally a minor component of a farming operation, and as such is easy to overlook during the season, especially now as other pests are requiring more attention and corn is nearing harvest. However, there are two significant insect pests that need to be scouted for to avoid potential losses and both are active right now on Delmarva. 

A fall armyworm outbreak is occurring throughout Virginia, Kentucky, and Ohio. This week, we received a report of armyworm damage to sod from Maryland’s Eastern Shore as well as residential lawns in Lewes, Delaware. This appears to be one of the most significant armyworm flights in many years. Scout turf, sod, pasture grasses, any late sweet corn that has not yet headed, and when the time comes, small grain and cover crops. Females lay egg masses containing between 50 and 200 eggs, meaning damage can be localized and intense and that it does not take many moths to infest a field. It is important to catch an infestation as early as possible. Larvae consume 80% of their total intake during the last three days of larval development. Often, it is during this period or just after larvae have finished that damage is noticed, occurring seemingly overnight as if an army had stripped the field. It takes about 14-19 days for larvae to mature.

Insect Pest Management in Peppers

Insect Pests of Tomato

Potato production in Maryland continues to grow and has more than doubled in the last 5 years, while in surrounding states it has declined. About 50% of the potatoes harvested in Maryland are for the fresh market while the other half goes for processing. Because of its value growers frequently apply pesticides too often in order to protect their investment. This often leads to the development of insect resistance, environmental contamination, worker and food safety concerns and poor management of pests.

A few hot spots where corn earworm (also known as tomato fruitworm, soybean podworm, and sorghum headworm) activity is starting to rise have been identified in central Maryland. The relatively mild 2020-2021 winter allowed adult moths to overwinter in Maryland, and some parts of the state experienced a higher than normal first flight in early June.