Veg Weekly Update and Blog 8/5/2024

All/multiple crops: Spotted lanternfly (SLF) adults are showing up in multiple vegetable crops in Orange County. While their presence may be alarming, SLF populations typically do not cause serious injury to vegetable plants. However, SLF do pose a risk to many perennials like grapes and certain tree species. Growers in Orange, Dutchess, and Ulster counties do NOT need to report sighting of SLF on their farms; squish individuals when possible. Growers in counties further to the north SHOULD report SLF sightings to the Department of Agriculture and Markets; more information on how to collect a specimen and make a report can be found in the “Take Action” section here. If you also have grape vines on your farm and are considering chemical control options, the NYS IPM program has a list of available pesticides for use on SLF in grapes here.

Alliums: More moderate temperatures and long periods of leaf wetness increase the risk of stemphylium leaf blight spreading in onions. Refer to Christy Hoepting’s onion fungicide cheat sheet for management options. As early onion varieties dry down and are harvested, adult onion thrips are also looking for new hosts and can become concentrated in fields of later varieties. Growers who experience a large influx of onion thrips adults this late in the season can consider applying Exirel at 20.5 fl oz/acre (note that IRAC 28 diamide insecticides are very effective at knocking down thrips populations, but that the chemistries can take 24-48 hours to reduce feeding pressure) or a tank mix of a labeled pyrethroid like Warrior II at 1.92 fl oz/acre with Lannate at 3 pts/acre. Heavy rains can also help to regulate thrips pressure in onions, so perhaps that is the silver lining to the short-term weather forecast.

Brassicas: Areas with heavy rain are seeing boron deficiencies in some fields, resulting in hollow stems. Foliar testing to ensure adequate boron, or a foliar application, may be warranted in fields with historically low boron levels.

 Chenopods (Beets, Chard, Spinach): See boron comment above- same issue applies in beets, resulting in deformities due to cankers.

 Cucurbits: Powdery mildew pressure is growing across the region as vines invest more energy into the developing fruit. This year’s table of powdery mildew fungicides can be accessed here.

Plectosporium levels are higher than usual on pumpkins in the capital district. A tight spray schedule for powdery and downy mildew should also pick up this disease.

Nightshades: Signs of Verticillium Wilt have been observed in eggplants. Yellow blotches on lower leaves, often V-shaped, may be the first symptoms followed by dark brown dead spots. Diagnosis involves making a vertical slice of the main stem near the soil line and observing a brown streaking in the vascular tissue.  More on this disease can be found by clicking here.   Blossom drop was noted in eggplant crops this past week. Blossom drop may occur when plants are stressed from lack of water. Eggplants require a minimum of 1 inch of water per week (including precipitation). During hot spells water requirements increase. Consider your soil type. Sandy soils drain very efficiently and therefore require more frequent applications than clay or silty soils. Hot humid weather can also impact pollen production and quality leading to blossom drop.

Diagnosing and Managing Verticillium Wilt in Eggplant
Ethan Grundberg

Eggplant growers around the region may be beginning to notice Verticillium wilt symptoms in their fields. Since Verticillium wilt infects the plant’s vascular system and restricts the movement of
water and nutrients, the associated leaf scorching and plant wilt symptoms are usually more pronounced during warm weather and in dry soils. Even though there is nothing that can be done to
cure currently infested crops, it is important to scout and record where Verticillium is present on the farm to inform a long-term management strategy.

There are two common soil-borne fungal pathogens, Verticillium albo-atrium and Verticillium dahlia, that cause Verticillium wilt in over 200 different plant species. Once the pathogens are
established in a field, they can survive for up to 15 years as microsclerotia in the soil and can continue to reproduce on a wide range of host weed species that includes velvet leaf, horse nettle,
pigweed, and lambs-quarters. The Verticillium species can be spread from field to field on equipment carrying soil, so care must
be taken to work fields with known infestations last and sanitizing equipment afterward.

On eggplant, the first noticeable symptom of Verticillium wilt is a discoloration on the edges of lower leaves accompanied by slight wilting. As the infection progresses and the vascular system
clogging becomes more severe, the discoloration can progress into more severe leaf scorching. These leaf symptoms are often only observed on one half of the leaf or plant, with one side visibly
wilted and necrotic and the other side seemingly healthy. Cutting the main stem of the plant just above the soil line will reveal a darkened center (the clogged vascular tissue). Though affected
plants may be able to survive, the loss in foliage often leads to secondary issues like sun scald on the fruit.

Management options for Verticillium wilt are limited, but there are some strategies that can be combined to maintain production in infested fields.

• Rotate infested fields into broccoli, corn, wheat, and/or barley for at least two years. These plants are not hosts and can reduce the level of inoculum while yielding a cash crop.

• Plant high isothiocyanate (ITC) concentration biofumigant mustards, such as the variety Caliente, incorporate the residue, and pack the soil. High ITC biofumigants can suppress
Verticillium species, even as microsclerotia

• When rotating back into a cash crop that is susceptible to Verticillium wilt, promoting robust root growth early in the season by increasing fertilization levels and, depending upon the crop and
soil type, using root stimulant products containing kinetin and/or Indole-3-butyric acid (IBA) rooting hormone can help plants produce a crop, even if
infested.