Vegetable scouting sheets can be found on the UMass Extension Vegetable Program website. When not given here, refer to the New England Vegetable Management Guide for scouting thresholds and treatment options.
Allium: White rot was diagnosed in garlic on one farm in Chittenden Co., VT. This fungal pathogen produces sclerotia that can survive up to 20 years in the soil without a host, making it very difficult to manage. The most effective way to avoid this disease is to plant seed from sources with no history of white rot into uninfested fields. Hot water treatment of garlic cloves at temperatures 115-118°F will greatly reduce the amount of pathogen present and is a good preventative measure, although it may not completely eradicate the fungus. Garlic germination will be inhibited above 120°F, so careful management of water temperatures is important. Leek moth larvae and damage continue to be reported in Chittenden Co., VT where this pest has become established over the last few years.
Basil: No new reports of basil downy mildew this week.
Brassica: Black rot has been diagnosed at the lab in VT and is a continuing problem in several crops. Hot water seed treatment of fall crops is recommended to avoid this disease. Cabbage Aphid was found above threshold of 15% infestation in cupping cabbage in Hampshire Co., MA, likely overwintered in high tunnels and greenhouses with brassica crops. Diamondback moth and imported cabbageworm were found at threshold on Brussels sprouts but not on collards in the same field and at the same growth stage in Washington Co., RI. Scout your brassicas separately as there may be host preferences for these crops. Untreated cabbage at the UMass research farm in Franklin Co., MA had sustained a lot of damage from ICW and large larvae were present.
Corn: European corn borer trap captures continue to be low to none in western MA and NH but have climbed in Chittenden Co. VT to 7 this week. The field scouted in VT was below threshold. According to growing degree days, a second flight should occur soon: at 1400 GDD; first eggs 1450 GDD; and egg hatch 1550 GDD. After scouting last week above tassel infestation of 15%, one organic grower targeted ears and tassels with Dipel achieving successful control in Franklin Co. MA. To avoid impacting bees and other beneficials in pollen laden tassels, other growers may use Belt or Coragen. Scout fields with tasseling and silking corn now and treat at a threshold of 15% infestation. A simple sequential scouting guide is available at the UMass Vegetable program website here: Sweetcorn IPM Guide. Corn earworm is being captured in central and south eastern MA at 3-5 moths per week, calling for a 5-6 day spray interval. Southwesterly storms this season has brought this pest into New England earlier than in the last several years. See article in the July 2nd issue of Vegetable Notes on corn earworm management options. Fall armyworm traps in MA, VT and RI continue to capture 0 moths, and only one location in NY is reporting any captured moths this week.
Cucurbit: Cucurbit downy mildew was reported this week on cucumber plants in Orleans and Allegany Cos., NY and in Berks Co., PA. Disease development is favored by just the sort of wet conditions and cool night-time temperatures we have seen quite a bit of so far this summer. Track the arrival and forecast risk of this migratory disease at: http://cdm.ipmpipe.org/. Current risk for CT, RI, Southern MA and Cape Cod is low and no risk in the rest of New England. When the forecasting program predicts a risk of CDM in your area consider switching to targeted, materials such as Ranman, Gavel, Curzate, Tanos, Forum or Zampro. Powdery Mildew was confirmed on Waltham butternut in Franklin Co., MA. Broad spectrum fungicides used to protect crops against cucurbit downy mildew are also effective at protecting crops for powdery mildew, however, once powdery mildew is present on 1 leaf out of 50 scouted in a field, targeted, mobile (to reach the underside of the leaf) fungicides are recommended. Striped cucumber beetle pressure was low in organically managed fields scouted in Hampshire Co., MA, Washington Co., RI, and Chittenden Co., VT. Squash vine borer trap captures have dropped into the teens in 25 out of 27 traps in NH, remain steady in MA and are climbing in RI. Due to rain this week fields have not yet been scouted for eggs or larvae, and damage has not yet been reported by growers. In years with mild temperatures such as we are having this summer, SVB adults tend to remain active throughout the summer rather than dropping off in summer then returning again to infect fruit in late-August and September. Fields of bush type cucurbits with trap captures of 5 or greater and fields of vining crops with trap captures of 12 or greater should receive evening sprays targeted at base of the plant. Squash bug adults but no eggs found in Chittenden Co., VT, and few adults and egg clusters found in fields scouted in NY, Hampshire Co., MA and Franklin Co., MA.
Solanaceous: Late Blight (Phytophthera infetans) was newly confirmed in Chittenden Co., VT, Wyoming Co., NY and Morris Co., NJ this week on potato. These recent samples have not yet been genotyped but US-23 was confirmed on potato in Livingston Co., NY last week. This strain affects both potato and tomato, so both crops should be considered at risk, and is sensitive to metalaxyl. Begin protectant sprays for LB now, if you have not already started. Several forecasting and decision support systems are available for growers, read about them in the June 25th, 2015 Vegetable Notes article on Forecasting Tools for Late Blight Management. According to the Massachusetts Late Blight Decision Support System, a 5-7 day spray interval on potato and tomato is recommended in most locations across the state. Early Blight was diagnosed on ‘Dusky’ eggplant in Chittenden Co., VT. This is the second diagnosis of this disease on this variety this year so the disease may have been seed borne. Use hot water seed treatment to prevent this disease on your crop next year. Bacterial leaf spot was confirmed on pepper in Chittenden Co., VT. This disease spreads quickly with rain splash and in humid weather. If seed-borne, it may start in one cultivar and spread to others. Make copper applications to prevent the spread of this disease. Three lined potato beetle larvae and adults were seen causing damage on tomatillo in Chittenden Co., VT. Eliminate nearby weeds in the solanaceous family, especially Physalis, also called husk tomato or groundcherry.
Multiple: Potato leafhopper was reported causing hopper burn in beans and strawberries in Washington Co., RI, on potato in Plymouth Co., MA, and on young apple trees in NH. Nymphs and adults have been seen in all locations. Plant later successions of beans away from the first successions, as this pest will continue to cause damage on younger successions next to infested crops.
Weeds: Breakdown in weed control has been seen throughout New England with the high rainfall we have been receiving. Weeds such as crab grass can be very aggressive, especially in crops under 1 ft. tall. Reapply herbicide or cultivate if needed at this stage.
