Vegetable Scouting Report: July 17, 2025
Alliums: Thrips pressure is increasing in many areas, so be sure to scout your onion crops and spray as needed to help them finish strong. Note that rain check can be mistaken for thrips if you have had any wind/rain events, so verify that you actually have thrips by checkin in the leaf axils. The threshold for controls is on average 2 thrips per leaf.
Some early varieties are going down now. If you are growing onions on plastic, consider opening up holes to provide better ventilation or remove the plastic entirely. This will reduce the bacterial rot known as slippery skin.
Brassicas: Nothing new to report- keep doing what you are doing!
Cucurbits: Late last week we confirmed Cucurbit Downy Mildew (CDM) on two farms in Washington County, both on cucumbers. This week we’ve gotten confirmations from Massachusetts and Long Island, also in cucumbers. We can assume that spores are widespread and that everyone in the region should be protecting susceptible crops. If you are growing cucumbers, Ranman and Orondis Ultra remain the top products to use, tank mixed with a protectant like chlorothalonil or copper. Mancozeb can also be substituted as the protectant on younger plantings as it has a 5 day pre-harvest interval. All stages of cucumbers are vulnerable and need to be protected. This strain or clad of CDM can eventually move into other crops such as melons, pumpkins and winter squash, but is much, much slower to develop. Protectant sprays should provide pretty good control in these crops. Organic growers can protect susceptible crops with copper tank mixed with Regalia.
Many pumpkin and winter squash plantings are getting ready or in some cases, have already begun to set fruit. That is usually the sign to start scouting aggressively for Cucurbit Powdery Mildew (CPM). Recommendations have not changed dramatically this year with Vivando (FRAC Group U8) being the key material rotated with Procure, Proline (both FRAC Group 3) or Prolivo (FRAC Group 50). Make sure to use the higher labeled rates and always mix with a protectant like chlorothalonil. Aprovia Top or Luna Experience could also be rotated in but these are pre-mixes of two materials in which one of the mixing partners is in the FRAC Group 3, same as Procure and Proline so use according when planning your rotations. For more information click here.
This week there have been a few calls about post emergent grass control in pumpkins and winter squash. There are a few products labeled such as Section 2 EC or Cleanse 2 EC, both containing the active ingredient clethodim. These products require a crop oil concentrate (COC) at 1% v/v in the finished spray volume or 1 gallon COC per 100 gallons of water. The label also states that a minimum of 10 gallons of water per acre with a maximum of 40 gallons per acre be used with a minimum spray pressure of 30 PSI with a maximum of 60 PSI. Do not use more than 8 fluid ounces per application to cucurbits with a maximum rate of 32 fluid ounces per acre per year. Do not tank mix with broadleaf herbicides or apply a post-emergence broadleaf herbicide within one day following application of or reduced grass control may result.
There are other grass materials labeled such as Poast, Poast Plus and Select Max – be sure to read the label as the adjuvants required may be different. For example, Select Max requires a Non-ionic Surfactant (NIS) at 0.25% v/v in the finished spray volume or 2 pints per 100 gallons of water.
Nightshades: Spider mite outbreaks are ramping up dramatically in high tunnel tomatoes, particularly where beans and cucumbers served as first hosts and are now providing a reservoir of mites. It is important to control outbreaks as soon as they are observed, because control is challenging even with the most effective products. You can use biologicals to limit low levels of infestation, but once levels are higher, chemical control is recommended. Organic growers can use neem (Azadirachtin) based products for supression, and conventional growers are recommended to use Portal (Fenpyroximate). Remember that control is likely to require multiple applications because eggs will not be controlled and will lead to a second wave of mites. Also please note that Portal has a 7 day PHI and plan harvests accordingly.
Sweet corn: This week we continue to trap high numbers of Corn Earworms (CEW) with many sites requiring a 4-5 day spray schedule. With daily high temperatures above 82°F the last couple of weeks, spray schedules should be tightened by one day. For example, moth trap captures are calling for a 4-5 day schedule, but since the temperatures are so high, we should be using a 3-4 day schedule, especially during the first 10 days of silkng. Each female moth is capable of laying between 500 and 3,000 eggs directly on the silks It is very important that you start your coverage when about 10% of the silks first appear and continue coverage until silks start to dry down. Remember that silks can grow or emerge as much as 1.5” per day and our insecticides only protect that silk that has emerged. As the silks continue to emerge we must reapply in order to maintain that protection which is why paying attention to trap catches is important. Besiege or Elevest continue to be the work horses of the spray program for CEW. Do not rely on pyrethroids such as lambda-cyhalothrin (Warrior II), beta-cyfluthrin (Baythroid XL), zeta cypermethrin (Mustang), bifenthrin (Brigade) by themselves. Tank mixing Lannate or one of the spinosyns such as Blackhawk, Entrust or Radiant with one of the pyrethroids above can also be a rotation partner to Besiege or Elevest.
Sap or Picnic Beetles have also arrived this week around the region and can especially be found in corn that has any kind of bird or insect damage to the tips of the ears. Usually the sprays used for Corn Earworm control these beetles as long as they contain a pyrethroid as mentioned above. Using Coragen alone will not control sap/picnic beetles.
