Vegetable Notes 2026 Vol. 38:8

Colorado potato beetles (CPB) were observed laying eggs in Norfolk Co this week. CPB emerge from overwintering sites in soil and brushy borders near last year’s crops and search for eggplant and potato crops to mate and lay eggs. The adults are poor fliers and do not travel far from overwintering sites, so crop rotation is essential to effective CPB management. Eggs are bright yellow-orange and are laid in clusters on the top and bottom sides of leaves. They hatch in 7-10 days, and reddish-orange larvae begin feeding heavily on leaves. Newly hatched larvae are most susceptible to insecticides, while larger larvae cause 85% of feeding damage to the crop and adults are highly tolerant to pesticides, so early management targeting the smallest larvae is critical. Make sure to rotate pesticides, as populations quickly develop resistance to any frequently used products, and don’t use the same thing you used on your population of CPB last year. There are enough options for conventional growers to do this, see the eggplant or potato insect management sections of the New England Vegetable Management Guide for labeled materials. Incipio, a newly registered foliar insecticide, is labeled for control of CPB on the fruiting vegetable crop group (which includes eggplant) at 2.1-4.1 fl oz/A and the same active ingredient is labled for potatoes as Zivalgo at 0.7-2.0 fl oz/A. For more information, see the article in last week’s Veg Notes. For organic growers Entrust SC is the most effective but should only be used on the spring generation—make sure to get the most out of your 2 allowed applications by waiting for the eggs to start hatching and making another application 1 week later.

Click on photos to enlarge and see descriptions.  

Solanaceous flea beetles are out and feeding on their preferred crop, eggplant, now. They will also feed on tomatoes, potatoes and, more rarely, pepper. Like brassica flea beetles, solanaceous flea beetles (FB) chew tiny holes in leaves that are magnified as the leaves grow and appear as larger holes later in the season, though this is less of a concern on crops where leaves are not the marketed product. Seedlings, nightshade crops like managu whose leaves are the marketed crop, and crops in tunnels and greenhouses are more susceptible to damage from this pest. Treat newly set transplants if they have 2 FB per plant, seedlings 3" to 6" tall if they have greater than 4 FB per plant, and plants over 6" tall if they have 8 FB per plant. Most insecticides registered to control Colorado potato beetle, including spinosad, systemic insecticides applied to the soil at planting, and the newly registered Incipio, will also control FB. Avoid using the same chemical group for both soil and foliar treatments.

Berry Blast

Berry growers can’t catch a break. This week temperatures are warm again before cooler conditions and potential rainstorms return later in the week. With bloom and early fruit development happening across multiple crops, growers should continue monitoring for diseases, insect damage, pollination, and fertility all together. Warm weather should help pollinators, but rain later in the week may favor pathogen development. In the commercial sector, domestic berries from California, Florida, and North Carolina have hit the market. Grocery stores are now stocking domestic strawberries, blueberries, grapes, blackberries, and raspberries. 

Strawberries are in full bloom with some early varieties pushing fruit development. Insects are starting to appear, and Botrytis has been spotted in some locations as the season progresses through fruit development, so be sure to have your fungicides and insecticides at the ready. During fruit development, excess water can also lead to fruit bursting. Be cautious during this time with your irrigation regimen. Fresh local strawberries are starting to appear slowly in farmstands and stores across the state with prices ranging from $6-8/pint. Pennsylvania farmstands are currently selling early-season strawberries at $9/pint. Yes pint, not quart. Things to consider as farm stands begin to open. 

Blueberries are between petal fall and full bloom, depending on the variety. Continue scouting and monitoring for mummy berry and Botrytis outbreaks this week. We are in the fertilizer application window now. The recommendation is to split applications into two parts; one in May and one in June. Calculate your fertilizer needs based on your soil test recommendations. Leaf analysis will come later in the season. Ammonium sulfate or urea are the common nitrogen sources; ammonium sulfate is a good fit where soil pH is still high. Avoid using aluminum sulfate as a fertilizer source.

Grapes are in rapid shoot growth and moving into pre-bloom. Continue watching for Phomopsis, black rot, and powdery mildew, as young shoots and developing clusters remain susceptible during this period. The Fruit Team will be having our final Twilight Meeting on June 3, 2026, from 4-6pm at Cold Spring Orchard in Belchertown. It will be vineyard-driven, focused on key management decisions during rapid shoot growth and the lead-up to bloom. Hope to see you there.

Brambles continue moving quickly with black raspberries now showing open flowers on floral canes and primocanes sprouting from the ground. Growers beginning their fertility programs should avoid excessive nitrogen rates, as this can push dense growth which may cause increased disease pressure in the future. Depending on your specific growing method, start managing your cane density and work on your trellis system if it needs maintenance before canes get heavy. 

Final thoughts: We are entering pathogen season. Continue scouting early and often. Problems are much easier to manage before they get out of hand. And always, be safe out there.

More Resources:

• Current bud stages (berry) - May 26, 2026

• New England Small Fruit Management Guide

--Written by J. Galvan  

Vegetable Notes. John Galvan, Maria Gannett, Genevieve Higgins, Lisa McKeag, Susan Scheufele, Alireza Shokoohi, and Hannah Whitehead, co-editors. All photos in this publication are credited to the UMass Extension Vegetable Program unless otherwise noted.

Where trade names or commercial products are used, no company or product endorsement is implied or intended. Always read the label before using any pesticide. The label is the legal document for product use. Disregard any information in this newsletter if it is in conflict with the label.

The University of Massachusetts Extension is an equal opportunity provider and employer, United States Department of Agriculture cooperating. Contact your local Extension office for information on disability accommodations. Contact the State Center Directors Office if you have concerns related to discrimination, 413-545-4800.