Most of New Jersey has finally gotten rain and pop-up thunderstorms making conditions ideal for pathogens such as Phytophthora and Pythium on spring-seeded and transplanted crops. Unfortunately, Pythium 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. [Read more…]
May 20, 2021 Andy Wyenandt
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…]
April 8, 2020 Andy Wyenandt
Phytophthora and pythium control during wet weather
Most of New Jersey has been plagued by heavy regular rains and pop-up thunderstorms making conditions ideal for pathogens such as Phytophthora and Pythium. Unfortunately, Pythium 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.
Control of Phytophthora blight and Pythium are extremely difficult (even with the use of fungicides) in the wet weather conditions. In the past few years a number of new fungicides, with new active ingredients, have become commercially-available for use on multiple crops. Mefenoxam or metalaxyl, both once widely-used to effectively control Phytophthora blight has been hit by resistance issues around much of Southern New Jersey the past decade. Growers with a known history of mefenoxam-insensitivity on their farm should use Presidio, Previcur Flex, or Ranman plus a Phosphite fungicide in rotation in their drip application programs. Importantly, if mefenoxam has not been used in particular fields on any crop for a number of years (more than 5+) the fungus may revert back to being mefenoxam-sensitive and control with these products may return. Mefenoxam, metalaxyl, Previcur Flex, and the phosphites are the most systemic of the group and should readily be taken up the by plant via application through the drip. Presidio has locally systemic and has translaminar activity and should offer some protection of the root system via drip. Ranman has protectant activity and thus will offer some root protection where it comes into contact with. Orondis Gold (oxathiapiprolin + mefenoxam, 49 +4) is the newest fungicide available with a new active ingredient in a new FRAC group. Additionally, in past research trials, mefenoxam, Orondis Gold, Presidio, Previcur Flex, Ranman, Revus and the phosphites in rotation and/or tank mixes have offered very good control of the fruit rot phase of phytophthora blight.
[Read more…]
February 14, 2020 Andy Wyenandt
Phytophthora-tolerant and -resistant bell pepper variety trial reports
Phytophthora blight caused by Phytophthora capsici is one of the most economically important diseases in pepper, tomato, and cucurbit production in New Jersey. Each year for the past few decades Rutgers has evaluated new bell pepper cultivars and breeding lines for their resistance to P. capsici in field trials at the Rutgers Agricultural Research and Extension Center (RAREC) near Bridgeton, New Jersey, and in some years at research trials on farms near Vineland, NJ. The pathogen, an oomycete – ‘water mold’ is favored by warm weather and wet soils during the production season and can survive between seasons in the soil as oospores. Once found in a field, the pathogen can establish itself, and be very difficult to control even with the use of fungicides. Fortunately, in bell pepper, phytophthora blight resistant/tolerant cultivars have been commercially-available for over 20 years now and have been used extensively by bell pepper growers throughout the state. Each year, as mentioned above, Rutgers evaluates these bell peppers for their resistance to P. capsici in heavily-infested fields as well as evaluate each for their fruit quality characteristics (e.g., color, wall thickness, number of lobes, and development of ‘silvering’). Some important points to remember. The pathogen is consistently evolving because of its sexual activity (i.e., mating types and oospore production). The more researchers look into the pathogen’s genetic diversity, the more they seem to find. The pathogen can develop resistance to important fungicides. Insensitivity to mefenoxam and copper resistance have been know for a very long time. Finally, phytophthora resistant cultivars such as Paladin which have been used extensively in southern New Jersey for the past 20 years appear to be breaking down. Over the past few years a number of new phytophthora resistant/tolerant bell peppers with new sources of genetic resistance have been released and evaluated by Rutgers. Some of these new bell peppers also have varying levels of resistance to bacterial leaf spot, with one – ‘Playmaker’ having X10R resistance to bacterial leaf spot and tolerance to P. capsici. Because of the increased reports of bacterial leaf spot and copper resistance in recent years and the difficulty in controlling it alone, all bell peppers grown in NJ at some point will need to have to have X10R resistance and phytophthora blight resistance. Importantly, for organic bell pepper growers, if you have not already done so, you should be evaluating these new lines to see if they meet your needs. The easiest way to mitigate both diseases are to start with genetic resistance. Below are the bell pepper variety reports going back to 2005 for review.
For more information on recommended bell pepper cultivars please visit the Pepper Section in the 2020/2021 Mid-Atlantic Commercial Vegetable Productions Recommendations Guide.
By: Andy Wyenandt and Wesley Kline
May 31, 2019 Andy Wyenandt
Phytophthora blight control in wet weather
Most of New Jersey has been plagued by heavy rains and pop-up thunderstorms these past few days making conditions ideal for pathogens such as Phytophthora blight (P. capsici) on pepper, eggplant, tomato, and cucurbit crops. Now that the temperatures are starting to rise the threat of infection will only begin to increase. Unfortunately, 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 pathogen also has an increasing host range that also includes snap and lima beans, and all other crops, other than a few resistant bell pepper cultivars, lack any resistance to the pathogen.
Control of Phytophthora blight is extremely difficult (even with the use of fungicides) in the extremely wet weather conditions that parts of New Jersey. In the past few years a number of new fungicides, with new active ingredients, have become commercially-available for controlling phytophthora on multiple crops. Mefenoxam or metalaxyl, both once widely-used to effectively control Phytophthora blight has been hit by resistance issues around much of Southern New Jersey the past decade. Growers with a known history of mefenoxam-insensitivity on their farm should use Presidio, Previcur Flex, or Ranman plus a Phosphite fungicide in rotation in their drip application programs. Importantly, if mefenoxam has not been used in particular fields on any crop for a number of years (more than 5+) the fungus may revert back to being mefenoxam-sensitive and control with these products may return. Orondis Gold, mefenoxam, metalaxyl, and the phosphites are the most systemic of the group and should readily be taken up the by plant via application through the drip. Presidio has locally systemic and has translaminar activity and offers protection of the root system via drip. Ranman has protectant-like activity and thus will offer root system protection.
For more information on these fungicides and specific crop uses, please see the 2020/2021 Mid-Atlantic Commercial Fungicide Recommendations Guide.
May 31, 2019 Andy Wyenandt
Early-season Phytophthora blight control in pepper
Phytophthora blight typically develops in low-lying areas after a heavy rain and can spread quickly throughout the entire field. 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 the extended period of dry weather works against Phytophthora development, it can lead to Rhizoctonia root rot issues in newly transplanted plugs.
Cultural Recommendations
In general, planting on a ridge or raised, dome-shaped bed will help provide better soil drainage. In fields with known low-lying or wet areas, avoid transplanting in those areas all together. In fields with a known history of Phytophthora blight, plant ONLY resistant cultivars to help reduce plant losses. If mefenoxam-insensitivity is known to exist in a field/farm, plant only tolerant cultivars. Do not apply mefenoxam or metalaxyl in fields where insensitivity is known to exist.
[Read more…]
