Rutgers University | New Jersey Agricultural Experiment Station | Pesticide User Responsibility

Vegetable Crops Edition

Seasonal updates and alerts on insects, diseases, and weeds impacting vegetable crops. New Jersey Commercial Vegetable Production Recommendations updates between annual publication issues are included.
 
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May 24, 2021

Identifying and controlling leaf mold in high tunnel & greenhouse tomato production

Leaf mold occasionally appears in high tunnel or greenhouse tomato production in New Jersey. However, under ideal conditions the disease will develop in field-grown crops. The fungus will cause infection under prolonged periods leaf wetness and when relative humidity remains above 85%. If relative humidity is below 85% the disease will not occur. Therefore, the proper venting of high tunnels and greenhouses on a regular basis is important. The pathogen can survive (overwinter) as a saprophyte on crop debris or as sclerotia in the soil. Conidia (spores) of the fungus can also survive up to one year in the soil.

Symptoms of leaf mold on infected tomato plant. Note the bright yellow leaves and the olive-green spores developing on the undersides of leaves.

Symptoms of leaf mold on infected tomato plant. Note bright yellow leaves and olive-green spores developing on undersides of leaves.

[Read more…]

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May 24, 2021

Preparing for cucurbit downy mildew

In 2004, cucurbit downy mildew re-emerged in the US with a vengeance causing significant losses in cucurbit production. In most years prior to this, concern for CDM control was minimal, since the pathogen arrived late in the growing season (in more northern regions), or the pathogen caused little damage, or never appeared. After 2004, with significant losses at stake, and with very few fungicides labeled for its proper control, CDM became a serious threat to cucurbit production. Importantly, at the time, cucumber varieties with very good levels of CDM resistance were no longer resistant, suggesting a major shift in the pathogen population. Research done over the past 15 years has led to a better understanding of the pathogen. Recent research has determined that the CDM falls into two separate clades: Clade I and Clade II. [Read more…]

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May 21, 2021

Quick reviews of fungicide chemistries, FRAC groups, and fungicide resistance management

For a quick review on fungicides, FRAC groups, and managing fungicide resistance development please click on the links below.

Using tank mixes and fungicide rotations and information on FRAC group 4, FRAC group 7, and FRAC group 3 and FRAC group 11 fungicides.

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May 21, 2021

Preparing for cucurbit powdery mildew control

Cucurbit powdery mildew (CPM), caused by Podosphaera xanthii, is one the most important diseases of cucurbit crops throughout the world. The pathogen is an obligate parasite, just like cucurbit downy mildew, meaning it needs a living host in order to survive. In northern regions that have a killing frost in the fall the pathogen will die out when the crop freezes. Not being able to overwinter, the pathogen must be re-introduced each spring or summer in the mid-Atlantic region. The pathogen accomplishes this by re-infecting cucurbit crops in the spring as they are planted up the east coast starting in Florida, then the Carolina’s, Virginia, and so forth. By late May, as soon as cucurbit crops begin to germinate in the mid-Atlantic region, the potential threat for potential powdery mildew infections begin. [Read more…]

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May 21, 2021

Preparing for Pepper Anthracnose

Pepper Anthracnose

Pepper Anthracnose

Pepper anthracnose caused by Colletotrichum spp. has become a significant problem on some farms in southern New Jersey.

Unlike in tomato, where symptoms are only present in mature (red) fruit, pepper anthracnose can infect pepper fruit at any growth stage. Currently, there are no commercially-available bell or non-bell peppers with known resistance to anthracnose. [Read more…]

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May 20, 2021

Early-season Phytophthora blight and Rhizoctonia root rot control.

Phytophthora blight typically develops in low-lying areas after a heavy rain. Fortunately, this spring in New Jersey has been really dry – too dry thus far, but that does not need you don’t need to prepare for potential phytophthora issues down the road. This is particularly important if are in fields with a known history of Phytophthora blight. Although extended periods of dry weather works against Phytophthora development, it can lead to Rhizoctonia root rot issues in newly transplanted plugs, especially if those plugs remain on the dry side too long before watering. Symptoms of Rhizoctonia root rot appear as brown lesions at the base of the stem with those lesions eventually girdling the stem and extending about an inch above the soil surface. If transplants haven’t been treated the the cell flat prior to transplanting, apply a fungicide through the drip system soon after transplanting. [Read more…]

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