All/multiple crops:

Heavy dew and prolonged wetness in crop canopies as the season progresses will increase disease pressure into the fall. As noted below for cucurbits and other crops, growers are encouraged to maintain fungicide programs to protect crops before harvest and maintain quality.

Alliums: 

As noted last week, the fall flight of allium leafminer is expected to begin in early September. Row cover or exclusion netting should be installed ASAP to prevent adults from laying eggs in scallions and leeks. Additional information on insecticide application timing will be shared once the start of the flight is confirmed, but 2-3 applications starting 2-weeks after the beginning of the flight period are effective.

The third (final) flight of leek moth has ended in the north and caterpillar feeding damage is visible in late season alliums, including scallions, leeks, and chives. Entrust (with 2(ee) recommendation), Lannate LV, Radiant SC, and Warrior II are labeled for use against leek moth. If onions have not been harvested yet, the plants can be topped before bringing in from the field to avoid infestation of the bulbs from leek moth brought into storage areas.

Brassicas:

More Alternaria Leaf Spot this week so be sure to pay attention to your fungicide program in your late brassica plantings. A note from an organic grower last week: they indicated that they were having success managing Alternaria with weekly rotating applications of OSO 5% SC at 6.5 fl oz /acre (0 days to harvest) with Double Nickel at 6 oz/acre. The OSO 5% SC label clearly states that “A rate of 6.5 fl. oz./acre may be used for preventative applications before onset of visible disease, in periods of low disease pressure, or in a tank mix with other fungicides for resistance management. Otherwise, use a rate of 13.0 fl. oz./acre.”  For more fungicide information, consult Cornell Vegetable Program Vegetable Specialist Christy Hoepting’s Brassica Alternaria Fungicide Cheat Sheet for more recommendations. This new 2024 cheat sheet reflects resistance to boscalid observed recently.

Several cases of black leg (phoma) have been observed in the Hudson Valley. The disease can be seedborne, so note if symptoms are predominately observed on one variety before spreading. Rotate out of brassicas in fields where symptoms are present for at least four years. Cabrio (pyraclostrobin) is the only labeled fungicide in NY.

Chenopods (Beets, Chard, Spinach):

Cercospora leaf spot is showing up on beet greens where fungicides have not been applied. The presence of this disease on foliage can make marketing bunching beets or Swiss chard a challenge. This leaf spot is easily identified; look for round light tan lesion within a red ring. For organic control of Cercospora, the most effective combination of products is copper octanoate + Bacillus amyloliquefaciens strain D747. Note, this is using both products tank mixed—the two used separately as a rotation were not as effective. The trial used Cueva and Double Nickel, but other formulations of copper and B. amyloliquefaciens may also be effective. For conventional control of Cercospora, it is first important to note that strobilurins are no longer effective. The most effective controls now are benzovindiflupyr + difenoconazole (Aprovia Top) or propiconazole (Tilt). For more information in Spanish or English, click here.

Cucurbits:

Many fall crop plantings are looking rough this week, mostly due to these crops maturing a bit earlier than some of you may have wanted. The heat this summer has progressed these crops anywhere from ~10 days to 2 weeks. If you missed it last week, click here for some tips on when to know if your crop is mature and how to best handle it. Even though the crop might be maturing and you will be harvesting soon, be sure to maintain a fungicide program until you are ready to harvest – it might sound strange, but you need to maintain as much foliage as possible to prevent sunscald, a problem that has gotten worse in the last 5 or 6 years due to our longer, warmer, bright sunny falls. More reports of Cucurbit Downy Mildew moving into pumpkins and winter squash also continue to come in so if you are still a couple of weeks out with your later plantings of vine crops, might be a good idea to include the CDM specific fungicides that can be found by clicking here.

Nightshades: 

Late blight was identified in two locations in Vermont near the NY border this week, and conditions are very favorable for disease development and spread. We recommend all growers make sure tomatoes have good coverage with a preventative fungicide such as copper (organic) or chlorothalonil (conventional). As a reminder, late blight symptoms generally start at the top of the plant and can cause quarter sized, watersoaked lesions on leaves and stems, and brown lesions on fruit.

Septoria Leaf Spot has been increasing lately in conventional tomato plantings. Most fungicides that are labeled for Early Blight are also labeled for Septoria Leaf Spot. Septoria lesions are generally small, black and numerous on the lower leaves of the plants.  Good control is important in order to maintain foliage on the lower leaves to protect the fruit from getting sunscald and from general defoliation. It’s hard to get good coverage on those lower leaves, especially in staked and tied plantings. Use adequate spray pressure and 30-40 gallons of water per acre to help with coverage.

And as expected, lots of fruit cracking, both radial and concentric showing up in the last couple of weeks as a result of the rains. More rain checking is also showing as a result of the heavy morning dews. And for those of you growing tomatoes on raised plastic mulched beds, don’t forget to keep irrigating tomatoes, peppers and eggplant! Just because we received those rains, doesn’t necessarily mean the beds are adequately moist. Wide fluctuations in moisture can also contribute to fruit cracking.

Potatoes: 
A few calls coming in on harvested potatoes in regards to Common Scab, an annual disease that shows up on tubers at harvest. There is not much you can do now except to start planning for next year–your ffirst defense is to choose varieties that have good scab tolerance.  Second, maintain adequate soil moisture during the setting time and enlargement. With the dry period many of us went through in July, there will be probably a lot of scab out there this year.  And third, try to maintain a pH below 6.0 if possible. Fourth, use good, clean, certified seed!

Corn:

Corn Earworm counts in some areas have gone sky high and is no surprise. Most corn in the Capital District and surrounding areas should be on a 3 – 4 day spray schedule. Fall Armyworm catches in some areas are also on the rise, but damage has been seen for a couple of weeks now. Targeted sprays for CEW should also control FAW. Last week we mentioned Northern Corn Leaf Blight and right on cue, NCLB was found in sweet corn late last week. There are numerous fungicides labeled for NCLB – however, you need to pay attention to the active ingredients as many of these are pre-mixes of the same active ingredients. The second thing to pay attention to is the days to harvest on some of these materials as some of them are as long as 21 days which is fine for younger corn, but not corn that you might be picking in a week! If you need help, don’t hesitate to give Chuck Bornt a call at 518-859-6213.  Most of these are compatible with your insecticides so they can be tank mixed.

This week’s sweet corn trap counts: