All/multiple crops:

Wet weather is likely to continue to spread many diseases this week, so growers are advised to maintain a protectant fungicide on cucurbits and solanaceous crops in particular. As you reach the point of making multiple sprays of protectant fungicides, consider alternating modes of action if possible. Conventional growers should consider alternating chlorothalonil based products with copper-based products or mixing the two, for example. Doing so provides a broader range of protection and helps with resistance management. Growers using products that are do not contain spreader stickers should consider adding one to help with maintaining coverage during this period of frequent rains.

Alliums: 

Stemphylium leaf blight (SLB) pressure is increasing in the region. More moderate temperatures, higher humidity, and prolonged leaf wetness are combining to create favorable conditions for SLB to spread this week. See Christy Hoepting’s onion fungicide cheat sheet for management options. Given the documented increase in resistance to the FRAC 3 products, it is generally being recommended to co-apply two different FRAC 3 chemistries together. For example, growers can apply a propiconazole product (Tilt, Fitness, OLF) with a tebuconazole product (Viathon, OLF) for the best results.

Garlic anthracnose is being found on recently harvested cloves. Cloves may feel soft to the touch despite the bulb appearing to be healthy and the wrapper leaves remaining intact. Early symptoms of garlic anthracnose are often observed during scaping. Little is known about how the pathogen spreads down into the bulb and potential management strategies.

Chenopods (Beets, Chard, Spinach):

Several cases of southern blight have been reported on beets in the Hudson Valley. The mustard colored sclerotia are key to identifying the disease. Southern blight can affect over 1,200 different plant species, so crop rotation is generally not a viable management strategy. Several conventional fungicides including azoxystrobin (Quadris), pyraclostrobin (Cabrio), and penthiopyrad (Fontelis) have been effective at reducing damage from southern blight when applied in furrow at planting. See this article from 2018 for additional information and images to assist with identification.

Cucurbits:

Incidence of Downy Mildew in cucumber plantings continues to rise in eastern NY. All cucumber and cantaloupe plantings should be protected at this time. The list of fungicides can be found by clicking here.  Look for yellow angular spots on the younger leaves and if conditions are damp and cool, a grayish mass of spores might be seen on the undersides of the spots.  ALL STAGES of plants are susceptible to the disease so make sure you are protecting all plantings and when you are finished harvesting a planting for the season, continue to spray with fungicides, mow or burn off with a non-selective herbicide so it does not become a spreader site for other plantings.

 Nightshades: 

Hornworm populations are increasing rapidly in tomato plantings. Scout the tops of plants for defoliated leaflets or damage to fruit or look for frass on the ground underneath plants. Hornworms are easily controlled when young with Bt products. Often one spray is sufficient to control hornworms in indoor plantings.

If you haven’t been conducting any foliar tests on tomato plantings, now is a good time to do so to detect nutrient deficiencies. Optimizing nutrition now can help plants to set a few more clusters of fruit and carry you through the end of the season strong. We do not endorse any specific labs but have had good luck with Waters Ag Lab. You can mail the 10 most recently expanded leaves along with a sample submission form to the lab and expect results within a couple days of the sample being received. Make sure to rinse leaves off if you use foliar nutrient sprays or copper, which will skew your test results.

Excessive heat has delayed ripening in some tomato plantings. The ideal temperature for fruit ripening is between 70-75^oF.  The ripening process slows significantly above 85-90^oF, or even stops. At these temperatures, lycopene and carotene, pigments responsible for giving fruit their orange to red appearance cannot be produced. As a result, fruit can stay in a mature green phase for quite some time.  After several days of excessive heat growers may notice blossom drop as well. Night temperatures over 72^oF can interfere with pollen formation and fruit set. So, is there anything you can do to hasten ripening?  Click here to read some suggestions from Dr. Steve Reiners of Cornell University.

Tomato fruit cracking often occurs when heavy rains follow a prolonged period of dry weather. Maintain even soil moisture through regular irrigation to avoid a sudden influx of water into the fruit which will lead to cracking.  Frequency of irrigation will depend on your soil type, the stage of the crop, and evapotranspiration rates. Cultivars vary in their ability to withstand cracking. Splitting is often observed on cultivars producing few but large fruits with high soluble sugars. High nitrogen and low potassium levels as well as temperature fluctuations (hot days/cool nights) may also be responsible for splitting. Adequate nutrition, timely irrigation, and mulching may help reduce cracking.

Corn:  As suspected Sap or Picnic Beetles have shown up in some sweet corn this past week.  They tend to infest the tips of ears where there may have been some damage from either a worm pest or bird damage or if the variety itself has poor tip cover.  Hot, humid days and warm nights really favor sap beetles, so conditions have been prime for infestations.  You might want to consider trying Assail (acetamiprid) in addition to your Corn Earworm insecticides for the last 1 – 2 silk sprays.  Assail will also control aphids if they are present.

Fall Armyworm damage was found in several plantings even though no moths were trapped, which is not uncommon!  FAW cause damage that you can’t miss – large, ragged holes with lots of brown frass develop as they burrow into the whorl of the plant.  They also prefer the younger corn that is close to whorl or in whorl stage.  This is a pest that moves up from the south on the prevailing wind and storm fronts.  They are resistant to synthetic pyrethroids so products like Warrior will not be effective.  Radiant, active ingredient spinetoram, IRAC group 5 (Insecticide Resistance Action Committee) or IRAC group 28 products and the carbamates (IRAC group 1A) like Lannate are also effective.  Once the worms enter the whorl, they are very difficult to get to so high-water volume to achieve good coverage and penetration is necessary.  Although older corn can tolerate quite a bit of damage, I have seen younger plantings suffer from heavy FAW feeding damage.

Most of the region remains on a 4-5 day spray schedule for silking corn to control Corn Earworms.  It is very important to maintain the coverage of the silk during this period.  Although products like Coragen and Besiege have some movement into the tissues, they do not translocate which is why as the silks continue to emerge, coverage needs to be maintained.

Western Bean cutworms trap catches also remain high this week.  Again, they prefer younger corn, especially those plantings just coming into whorl stages.  And like FAW, they burrow directly into the whorl and into the tassels, protecting themselves from insecticide applications.  Time insecticide applications when 50% of the tassels have emerged and started to open followed by a second application when the remaining tassels have emerged and opened.  Materials used for Corn Earworm are also effective in controlling WBC.

Miscellaneous: 

Some of you may be using copper fungicide formulations to manage fungal and bacterial disease in vegetables. Click here for information on How Copper Sprays Work and Avoiding Phytotoxicity