Cucurbit downy mildew has been reported on cucumber in Central New Jersey. This is the first report of CDM this growing season in the state. All cucumber and cantaloupe fields need to be scouted on a daily basis and preventative fungicide programs need to be initiated. For more information on CDM and its control please click here.
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July 11, 2025 Andy Wyenandt
Preparing for cucurbit downy mildew in 2025
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 19 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…]
July 11, 2025 Andy Wyenandt
Controlling Phytophthora blight in cucurbit plantings in 2025
As the summer heats up in New Jersey, the control of Phytophthora blight in cucurbit plantings can be extremely difficult (even with the use of fungicides) as hot, wet weather has set in these past few weeks. Mitigating losses to Phytophthora blight in cucurbit crops begins with long crop rotations, where recommendations suggest crop rotations longer than 5 years if possible. Other cultural practices include avoid planting in low areas of the field where water may persist after rain or overhead irrigation, rogueing out infected plants as soon as possible, cutting the plastic to help dry out the soil, proper weed control, and proper preventative fungicide programs.
July 10, 2025 Andy Wyenandt
Vegetable Disease Update – 7/10/25
Cucurbit downy mildew has been reported (7/11/25) on cucumber in central New Jersey. For more information on CDM and its control please click here.
Early blight has been reported in tomato.
Bacterial leaf spot (BLS) has been reported in bell and non-bell pepper. For more information on BLS please click here.
Tobacco Streak Virus and Tomato Spotted Wilt Virus (TSWV) have been reported in southern New Jersey. For more information please click here.
Collar rot on fresh-market tomato has been reported sporadically around the state over the past week. For more information please click here.
White mold and Southern blight have been reported this past week on fresh-market tomato in both high tunnels and fields in southern New Jersey.
There have been no reports of CDM in the region to date.
Wet weather brings on the development of Phytophthora blight.
Preparing for Pepper anthracnose this growing season.
July 10, 2025 Andy Wyenandt
Phytophthora and Pythium control during wet weather
Most of New Jersey has been wet making current conditions ideal for pathogens such as Phytophthora and Pythium. Unfortunately, Pythium cottony leak and Phytophthora blight can be found on most farms in the southern part of the state. Poor crop rotations with susceptible hosts only make matters worse. The Phytophthora pathogen has an increasing host range that now includes snap and lima beans; and all crops, other than a few resistant bell pepper cultivars, lack any resistance to the pathogen. Under ideal conditions (hot, humid, and wet) Pythium cottony leak can develop on infected fruit.
July 9, 2025 Andy Wyenandt
Bacterial leaf spot, copper resistance, hot water seed treatment, and viruses
Copper resistance in bacterial leaf spot of tomato and pepper crops has been detected at a high level in New Jersey the past few summers. While not surprising, copper resistance has been known to develop for decades now. Copper applications for the control of bacterial diseases in many crops has been a mainstay for decades now and is often applied in weekly protectant fungicide programs. With help from Dr. Nrupali Patel and Dr. Don Kobayashi, bacteriologists in the Department of Plant Biology located on the New Brunswick campus, a (NJ-VGA funded) survey was initiated to determine which species of bacterial leaf spot are most prevalent in New Jersey tomato and pepper crops. Bacterial leaf spot can be caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri. Currently, there are four races of BLS found in tomato (T1-T4; one for each of the 4 species stated above) and eleven races found in pepper (0-10). Differential tests in southern New Jersey using various bell pepper lines over the past 15 years has suggested that the number of races of BLS in pepper has increased over time; with all races present in the State to date. Lab testing results from samples collected from the small number of NJ vegetable farms the last three summers has shown the presence of X. euvesicatoria in pepper, as well as X. euvesicatoria and X. perforans in both tomato and pepper in the state, with ~60% of all samples testing positive for copper resistance.
