High Populations Of Insects In The East

potato field

Many species that overwinter in Pennsylvania apparently have done so with high survival rates. For example, we’ve seen very strong populations of several species of maggots, cucumber beetles, and asparagus beetle in April and May. However, many of our pests tend not to overwinter, but arrive as long distant migrants. We can now confirm that the long-distant migrants listed below have also been reported in May.

At our research farm in Centre County, we have found a few corn fields with substantial black cutworm damage. Black cutworms are primarily pests of corn, but they can also attack tomato, pepper, and eggplant. These caterpillars are active at night, but were easy to find with a trowel by digging up the cut seedling. Presence of the black, greasy looking caterpillars verifies the source of damage, which can be difficult to diagnose in some cases, particularly in slug infested fields.

To hedge against any surprises, growers and field personnel would be wise to scout fields for cutting damage, and apply rescue treatments if larvae are small and the economic threshold is exceeded. Females lay eggs in dead vegetation on the soil surface and in weeds, where moisture is high. Young larvae feed on the leaves of emerging corn, whereas the older larvae cut the plant off at the base or bore into the plant. In sweet corn, check each planting weekly during the spike through the five-leaf stage. Check for small irregular holes in the leaves, and missing or cut plants.

If cutworms are present, examine 10 sets of 20 plants throughout the field and record the percent of cut or damaged plants. Look under clods of dirt and vegetation and the bases of plants for the larvae; if you see the larvae, record the average size and the number per 100 plants. In sweet corn during the two-leaf stages, apply a treatment if more than 10% of the plants show fresh signs of feeding. At the three to four-leaf stages apply treatment at a 5% level.

Also, use your judgment based on stand count. If you are at the minimum stand count, you may need immediate treatment, whereas more feeding can be tolerated if the stand is heavier than needed. During drier conditions, treatments may be less effective because cutworms may be feeding below the soil surface. In these cases, rotary hoeing or cultivation, as well as using higher spray volumes, may help increase the chances of contacting the insects with the pesticide.

After four or five weeks, the larvae pupate in the soil. Two more generations may occur, but damage does not tend to occur from later generations, so no treatment is needed if the population is finishing its larval feeding stages and pupating. Full grown larvae are about 1.75 inches in length and although feeding damage increases with larval size, feeding will stop when they pupate. For more details on black cutworm see: www.ento.psu.edu/extension/factsheets/black_cutworm.htm.

True armyworms are also active. These caterpillars can cause damage to small grains and corn, but tend to be most problematic in corn planted before a small grain cover crop was completely dead. Be sure to scout for damage from this pest because, true to its name, populations can generate quickly and march through fields causing extensive damage — in corn characteristic defoliation leaves just the midrib remaining- For details, go to http://ento.psu.edu/extension/factsheets/armyworm.

This is a year where you need to be scouting your fields and be prepared for earlier-than-usual pest pressure.

Leave a Reply

Featured Stories

All Vegetables Stories >All Fruits Stories >All Nuts Stories >All Citrus Stories >

The Latest

BerriesReal Estate Firm, Wish Farms Strike Large Land Deal
October 1, 2014
$13.8 million transaction includes more than 800 acres acquired from longtime Central Florida produce operation. Read More
VegetablesFind The Right Market For Your Crops
October 1, 2014
Getting to know the demographics of your market is key to maximizing your return on investment. Read More
Insect ControlBagrada Bug And Brown Marmorated Stink Bug Posing Threa…
October 1, 2014
Two species of stink bugs are now posing a serious threat to agricultural production in the Western U.S.: the brown Read More
OrganicResearchers Breeding Organic Tomato Varieties Receive $…
October 1, 2014
Purdue University accepts funding to lead multi-institution research to breed organic varieties that will resist foliar diseases. Read More
Vegetables14 Quality Cabbage Varieties [Slideshow]
October 1, 2014
Browse the slideshow below for information on cabbage varieties from the nation’s leading seed breeders and distributors. Read More
FruitsOrganic And Local Food Economies Receive More Than $52 …
October 1, 2014
Most of the grants were authorized through the 2014 Farm Bill. Read More
Insect ControlMore Than 600,000 Acres Removed From Golden Nematode Re…
October 1, 2014
The potato acreage was taken off the Animal and Plant Health Inspection Service’s list; under 6,000 acres in New York are still considered to be infested. Read More
Crop ProtectionTool Helps Track Insects On The Move At Night
October 1, 2014
Signals collected by the National Weather Service’s Doppler radar network may serve as an early warning system to track corn earworm, a major pest in sweet corn. Read More
NutsNew Walnut Budding, Grafting, and Planting Video Releas…
October 1, 2014
Lake County nurseryman Alex Suchan, who has been grafting trees for two-thirds of a century, is the star. Read More
GenNext GrowersGrowers Need To Be Mindful When Dealing With The Media
October 1, 2014
When being interviewed for a story, preparation is the foundation to help you successfully get your point across. Read More
Citrus Achievement AwardSharing Is Caring When It Comes To Curing Citrus Greeni…
October 1, 2014
Mike Sparks, 2014 Citrus Achievement Award winner, says being open with peers about what's working and not working is crucial in managing HLB. Read More
Florida Ag ExpoKnow How To Knock Back Nematodes
October 1, 2014
The 2014 Florida Ag Expo will provide critical tips in soilborne pest management. Read More
CEU SeriesCEU Series: Vow To Vanquish Weeds Among Vegetables
October 1, 2014
Herbicidal neglect can and will kill your crops. Read More
Insect & Disease UpdateUF Names Interim Director For Citrus Research And Educa…
September 30, 2014
Michael Rogers has been a central figure in Florida’s battle to survive greening. Read More
BerriesPractice Persistence When Battling Botrytis In Blueberr…
September 30, 2014
Cognizance of resistance is key to managing formidable fungus. Read More
CitrusFarming Is Quite The Scary Prospect For Some [Opinion]
September 30, 2014
Florida Grower managing editor Paul Rusnak says economic realities might frighten off future leaders from noble professions. Read More
FruitsNew Suppress Herbicide Gets Green Light From EPA
September 30, 2014
Approval gives organic growers new weed management tool. Read More
BerriesNew Fill-By-Weight Clamshell Filler For Blueberries
September 30, 2014
Lakewood Process Machinery's equipment offers a simplified user interface, minimized drop heights, a new dribble-gate system designed for an increased level of accuracy. Read More