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.
Identifying and controlling leaf mold in high tunnel & greenhouse tomato production
Identifying white mold in greenhouse & high tunnel tomato production
White mold, or timber rot, is caused by the soil-borne fungal pathogen, Sclerotinia sclerotiorum.
The photo on right shows a high tunnel tomato plant with main stem infected by white mold. Over time the entire plant will slowly collapse looking similar to a wilt or root rot pathogen as the water supply is cut off to the plant.
White mold is common and once introduced into a field or high tunnel it can very difficult to control. The pathogen produces black sclerotia on the surface and inside infected stems. Sclerotia, if they make their way back into the soil, can survive for years causing significant problems.
Infected stems will turn a light brown color and dry up becoming brittle. If the main stem is infected the entire plant will collapse looking like a wilt or root rot issue.
Under hot, humid conditions white fungal growth will develop on the surface of the stems and in some cases sclerotia will develop on the outside of the stem. Breaking open the stem will reveal numerous black sclerotia.
All infected plants and or plant material need to be removed from the greenhouse or high tunnel immediately and disposed of properly. Preventative protectant fungicide programs beginning at flowering will help control white mold. Cool, wet weather and poor air circulation favors disease development.
There are a number of control options for conventional and organic growers listed in Table E-11 in the 2020/2021 mid-Atlantic Commercial Vegetable Production Recommendations Guide.
Allium leaf miner update: 04/09/20
Allium Leaf Miner
Allium leaf miner (ALM) adults were captured in higher numbers (16/week) on yellow cards in Princeton (Mercer Co.), NJ on Tuesday of this week, while lower numbers (2) were found near Milford, Hunterdon County. Additionally, a garlic field near Asbury on the Warren/Hunterdon border was found to have 64% of plants exhibiting feeding/egglaying scars. This indicates that the first (spring) flight of these flies is now in full swing, and damage is ongoing. ALM flies were observed on foliage in all fields that were inspected this week.
Growers should consider implementing the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks.
Floating row covers, kept on until this flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control. The diamide, Exirel, is permitted in NJ under a 2ee label as well.
Adult activity and observations of feeding will be reported on in the IPM Update as they occur. At this time, all growers should respond to the first adult generation. We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.
Allium leaf miner update: 03/24/20
Allium Leaf Miner
Allium leaf miner (ALM) feeding/egglaying scars were detected in chives near Princeton (Mercer Co.), NJ on Tuesday of this week. This indicates that the first (spring) flight of these flies has now begun and damage will increase. Additionally, extension personnel at Penn State have reported finding the first feeding scars in several southeastern PA sites within the past few days. It is believed that all of these occurrences are very recent.
Growers should consider initiating the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks.
Floating row covers, kept on until this flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.
Adult activity and observations of feeding will be reported on in the IPM Update as they occur. At this time, all growers should respond to the first adult generation. We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.
Allium leaf miner update: 09/20/19
Allium Leaf Miner
Allium leaf miner (ALM) feeding/egglaying scars were detected in chives and scallions near Princeton (Mercer Co.), NJ on Friday of this week. This indicates that the second (fall) flight of these flies is now underway, and damage is occurring.
Growers should consider initiating the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks.
Floating row covers, kept on until the second flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), and pyrethrin materials (Pyganic (OMRI approved)), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.
Adult activity and observations of feeding will be reported on in the IPM Update as they occur. At this time, all growers should respond to the second adult generation. We will attempt to identify the end of the second flight so that growers know when the risk of infestation has abated.
Allium leaf miner update: 09/20/19
Allium Leaf Miner
Allium leaf miner (ALM) feeding/egglaying scars were detected in chives and scallions near Princeton (Mercer Co.), NJ on Friday of this week. This indicates that the second (fall) flight of these flies is now underway, and damage is occurring.
Growers should consider initiating the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks.
Floating row covers, kept on until the second flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), and pyrethrin materials (Pyganic (OMRI approved)), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.
Adult activity and observations of feeding will be reported on in the IPM Update as they occur. At this time, all growers should respond to the second adult generation. We will attempt to identify the end of the second flight so that growers know when the risk of infestation has abated.