All crops: The main consideration on most people’s minds is the heat this week. A secondary consideration is ozone damage, which can present as a burned look on the surface of susceptible crops. To learn more about ozone damage, read this helpful article by Teresa: https://cornell.box.com/s/ixk0pvuvrkr3gjkzhj5vbez8vgd4j7y6

If you’d like a review of heat stress on crops, check out Dr. Reiner’s article here, which also features some mitigation strategies: https://cornell.box.com/s/tpajwtipqyz9zfi0hadx95e8gb1obbnj

Alliums: Nothing new to report

Brassicas: Flea beetle pressure continues to be high in some areas, with others experiencing a dip between generations. Timely sprays, especially to small plants, will help reduce economic damage. Overall disease pressure remains low.

Chenopods (Beets, Chard, Spinach): Nothing new to report

Corn:  Early silking corn can be found throughout the region, especially where rowcovers or plastic was used.  Scouting for European Corn borer should be concentrated on late stage whorl or emerging tassel state corn.  Look for window paning feeding damage.  Time insecticide applications on corn that has about 50% of the tassels just emerging followed by another application when the rest of the tassels emerge.  ECB is most susceptible at this point as they ride and try to burrow into the tassel.

Cucurbits:  Cucumber beetles continue to be found in many of our cucurbits again this week, but the numbers in general have started to decline.  There are reports of Squash Vine Borer activity increasing in New Jersey and other states.  SVB adults lay their eggs at the base of a squash or pumpkin plant and as they hatch, they burrow into the stem and begin to feed, causing the plant to wilt.  Sure signs of SVB include what looks like a pile of sawdust at the base of the plant and when you cut open the stem you will find a large white grub.  Once the damage is done there is no reversing it.  Preventative measures need to be taken which could include floating rowcovers on small plantings not being harvested or insecticide applications. Applying a pyrethroid, weekly for the next 4 weeks is the recommendation.  Coragen or a Spinosyn (Radiant, Entrust, Blackhawk) can also be used to help suppress vine borer.  Please be sure to time your insecticide applications when bees are not active in the flowers!

The hot weather has highlighted areas where bacterial wilt is an issue, especially in high tunnel cucumbers. Plants which wilted more than others during the heat this week may be showing signs of bacterial wilt infection. Once plants are infected there is no remedy, but in successive plantings protecting plants from cucumber beetle feeding (the vector for bacterial wilt) before they have 4-5 leaves will help prevent infections.

Nightshades:  The hot dry conditions along with of hay and straw cutting has really spiked the Leafhopper pressure in potatoes, beans and even eggplant with “hopperburn” symptoms showing up in these crops.  Even eggplant can be injured (marginal burning) by LF so be sure to scout them often as well.  Be sure to be monitoring your soil moisture, especially in your tomato crops – a lot of early plantings are beginning to set and size fruit and now is the time to be vigilant in order to reduce blossom end rot.  Blossom end rot is caused by a lack of calcium being delivered to the fruit.  In many cases, calcium is in abundance in the soil, but because it needs to be dissolved and taking up in the soil solution, dry soils or saturated soils can also be the cause and this week with the heat, plants may shutdown during the middle of the day which can also induce BER as plants are not taking water up.  It’s not easy trying to manage all of these factors, so control the ones you can!

This week’s heat should also coincide with aphid arrival as they prefer these kinds of conditions.  Products like Beleaf, Assail and Fulfill are all good insecticide choices. Fulfill is most effective when aphid populations are low and needs to be followed up with a second application about a week after the first.  Azadirachtin containing products or Pyganic are labeled for organic production.

We did see flower bud abortion due to the heat in many high tunnels this week. The temperatures were simply too high for ventilation and irrigation to prevent this particular event, but hopefully as temperatures drop again plants will quickly generate their next flower cluster.

Colorado Potato Beetle control is essential as populations increase and are driven to feed by the heat.  CPB can be difficult to control in larger instars and nearly impossible in adults, so your best chance is when larvae are small.  Rimon, Radiant and the chlorantraniliprole containing products (Coragen, Minecto Pro etc.) are still our best choices for conventional growers.  If using Rimon, apply 2 times, 7-days apart, at a rate of 12 oz/A at each application, starting at 50% egg hatch or when small larvae are first observed. For organic producers, Entrust or azadirachtin products (Azatin, AzaGuard, Azera, Molt-X, Aza-Direct, Ecozin Plus, Neemix) can be effective but need to be applied again when larvae are small. Apply these 2 times, 7-days apart, and apply at the highest labeled rate starting when small larvae are first observed. Products with the active ingredient Bacillius thuringiensis var tenebrionis are becoming available again and are excellent options. Novodor has been released by Valent as the first option, and can be applied at a rate of 1-4 quarts per acre.

Beans: Leafhopper numbers have exploded and snap beans in particular. When plants are small they can quickly become injured which can lead to major yield loss.  Thresholds for LH are very low – 1 per sweep. In fields scouted Tuesday numbers were between 5-7 per plant! Pyrethroids such as Warrior II, Mustang can be used, but multiple applications will probably be required.  Another labeled material such as Assail (acetamiprid) will give you a week or more of protection and might be a good choice for younger plantings.

Miscellaneous:

From Cornell University Assistant Professor of Weed Ecology and Management in Specialty Crops in the School of Integrative Plant Science’s Horticulture Section Lynn Sosnoskie:   Just a reminder that herbicide performance, as well as crop safety, can be affected by temperature.

The optimal air temperature for applying most post-emergence herbicides is between 65°F and 85°F. When the air temperature drops lower, plant growth, including that of weeds, slows down. This reduced growth leads to slower uptake and translocation of herbicides (i.e., slower symptom development/herbicide activity). At higher temperatures, weeds may be stressed, which can also reduce herbicide activity. Crop injury may be enhanced under hot weather conditions (injury may be exacerbated by adjuvant selection). Also, over 85 F, some herbicide may be more volatile and off-target movement (and unintended injury) may occur.

Blogs about herbicide use under dry conditions (which does mention temperature):

The Effects of Dry Conditions on Weed Management | Cornell Fruit Resources: Berries

Effects of dry conditions on weed management | CALS (cornell.edu)

Temperature and Herbicide Application Questions | NDSU Agriculture

Basil:  Basil Downy Mildew was confirmed in New Jersey this week so if you are growing basil, make sure you are scouting.  Initial symptoms include leaf yellowing followed by leaf browning.  Affected leaves also curl and wilt, and on the undersides of the leaves, a gray-purple fuzzy material will develop. Andy Wyenandt from Rutgers Cooperative Extension has a great article detailing the controls in both greenhouses and field basil production.  The link for this article can be found by clicking here.  Please note that Segovis can only be used on basil that is being sold as transplants and is not labeled for field use:  “Vegetable transplants can be treated with Segovis prior to retail sale only to residential consumers.”  As with any pesticide, please read the label to make sure you are using the correct rates and including any adjuvants that are required.