Botrytis, or gray mold, caused by the fungus, Botrytis cinerea, can cause significant losses in high tunnel and greenhouse tomato production if not controlled properly. The pathogen can rapidly spread during periods when structures are closed and when relative humidity remains high for long periods of time. This often occurs when outside weather remains cool and damp while heating is needed. Gray mold is favored by temperatures from 64° to 75°F and requires only high humidity (not leaf wetness) to become established. The pathogen has a large host range and once established in an enclosed structure it can be very difficult to control (UMASS). The fungus can survive/overwinter as mycelia or sclerotia in plant debris and in organic soil matter (NCSU).
Identifying and controlling botrytis in high tunnel and greenhouse tomato production
Identifying white mold in tomato production
White mold, or timber rot, is caused by the soil-borne fungal pathogen, Sclerotinia sclerotiorum.
High tunnel tomato plant with main stem infected by white mold.
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 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 2022/2023 mid-Atlantic Commercial Vegetable Production Recommendations Guide.
Tomato stem infected by white hold. Note the fungal growth on the surface of the stem.
White mold of tomato. Note the black sclerotia developing inside the brittle stems.
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 bright yellow leaves and olive-green spores developing on undersides of leaves.
Allium leaf miner update: 04/21/21
Allium Leaf Miner
Allium leaf miner (ALM) feeding/egg laying scars continue to increase in chive plantings near Milford, Hunterdon County and Lawrenceville, Mercer County as of this Tuesday. Chives in home gardens in central Morris County and southern Cape May County were also found to be infested this past weekend, with adults actively flying in plants. The first (spring) flight of these flies appears well underway. Yellow sticky cards have captured low, but consistent (range 1-5/card/week) numbers of adults in Hunterdon and Mercer County plantings. Foliar insecticide applications temporarily suppress catches on the cards. Growers throughout the state should assume there is egg laying activity in their area currently.
Growers should consider initiating (continuing) the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks. Look for neat rows of white spots descending from the upper tips of allium leaves (see photo at left). Initial injury often occurs on the tallest leaves. Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adults at lower right). Click on photos to enlarge the images.
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 weekly sprays have not stopped foliar injury. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom), the diamide Exirel (section 2ee recommendation) and the insect growth regulator Trigard are labeled for leaf 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 continue to 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: 04/06/21
Allium Leaf Miner
Allium leaf miner (ALM) feeding/egg laying scars were detected in a large chive planting near Milford, Hunterdon County on Tuesday of this week. Feeding was very low (<0.5% of chive clusters), but several adults were observed in the planting. This indicates that the first (spring) flight of these flies has now begun and damage will increase. No injury or adults were found in a similar inspection of a commercial chive planting near Lawrenceville (Mercer Co.) on the same day. Yellow sticky cards were deployed in both locations and will be checked weekly. We look to identify the peak of the flight in central and northern NJ, as well as the period when the adult population is in decline. Growers in southern counties should assume there is egg laying activity in their area currently.
Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion
The Milford and Princeton NJ weather stations that are closest to these farms both surpassed 250 growing degree days (GDD) base 39˚F on Monday (4/5). This GDD base is close to that (38.3˚ F) which our colleagues at Penn State recommend for predicting the first emergence of ALM adults.
Growers should consider initiating the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks. Look for neat rows of white spots descending from the upper tips of allium leaves (see photo at left). Initial injury often occurs on the tallest leaves. Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adult at lower right).
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.
Reflex 2SL received a 24(c) SLN label for transplanted peppers and tomatoes
A 24(c) Special Local Needs label has been recently approved for New Jersey for use of Reflex herbicide for Control of Weeds in Transplanted Tomatoes and Transplanted Peppers. The use of Reflex 2SL is legal ONLY if a waiver of liability has been completed on the Syngenta website (https://www.syngenta-us.com/labels/indemnified-label-login).
Reflex is a selective preemergence herbicide for broadleaf weed control with both soil and foliar activity, but it is only labeled for preemergence use in transplanted peppers and tomatoes. The active ingredient in Reflex is fomesafen, a PPO inhibitor and the only herbicide in this family labeled for peppers and tomatoes. Broadleaved weeds are the main targetted species of this herbicide, that also activity on nutsedge. Expect excellent control of pigweed, (including Palmer amaranth), common ragweed, nightshade, and common purslane, acceptable control of common lambsquarters, morningglories and galinsoga, and suppression of field bindweed and nutsedge at the rate labeled for transplanted tomatoes and peppers. Use of a surfactant will improves postemergence control of susceptible annual broadleaf weeds. Note that annual grasses and some annual broadleaf weeds, including spurred anoda or horseweed, will NOT be controlled by Reflex 2SL.
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