May 31, 2015

White Mold in Greenhouse & High Tunnel Tomato

White mold, or timber rot, caused by the soil-borne fungal pathogen, Sclerotinia sclerotiorum, was found this past week in a high tunnel.

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 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.

Tomato stem infected by white hold. Note the fungal growth on the surface of the stem.

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.

White mold of tomato. Note the black sclerotia developing inside the brittle stems.

Filed Under: Vegetable Crops Tagged With: ,
April 21, 2015

Early-season Pythium and Phytophthora Control in Pepper and Tomato Crops

“What should I do to help prevent Pythium and Phytophthora in my pepper and tomato crops early in the season?” is a question most often asked this time of year. In the past, the answer was simple. Apply mefenoxam (Ridomil Gold SL, Ultra Flourish, 4) or metalaxyl (MetaStar, 4). Problem solved, right?

Not exactly, with resistance development in Phytophthora (P. capsici) to both mefenoxam and metalaxyl, the correct answer isn’t as simple anymore. It’s important to remember that both chemistries will work very well as long as resistance hasn’t been detected on your farm. How do you know if you have resistance? The easiest way is to follow efficacy. [Read more…]

Filed Under: Vegetable Crops Tagged With: , ,
October 13, 2014

Late Blight Still Active on Tomato

Late blight was confirmed in a homeowner garden today near Clementon, NJ (Camden County) and here at the Rutgers research station near Bridgeton, NJ (Cumberland County). This is a good reminder that as long as weather conditions are conducive, the threat of late blight in the state and region will continue until the first killing frost.

All abandoned tomato fields need to be destroyed either by mowing, discing under, or sprayed with a herbicide such as gramoxone to kill all living foliage. This is especially important if protectant fungicide programs have been discontinued. Homeowners can simply pull plants and put in their compost pile or discard in the trash.

Filed Under: Vegetable Crops Tagged With: ,
October 13, 2014

Internal Fruit Rot in Tomato

A fresh market tomato from a home owner garden was dropped off the other day with some strange internal rot. The internal rot (photo 1) was most likely caused by water accumulating in areas immediately around the stem and as the fruit developed growth cracks (photo 2). This allowed for opportunistic fungi and bacteria into infect the fruit causing the internal rot. As it turned out the home owner was using sprinklers to water their garden.

As the season continues into the late fall, it might be worthwhile to slice up one or more of your tomato varieties that are prone to growth cracks around the stem just to check if this is happening in your operation – especially with heavy dews and the wet weather we have had recently.

20141003_102835

Photo 1: Internal Fruit Rot

20141003_102848

Photo 2: Growth Cracks

Filed Under: Vegetable Crops Tagged With: ,
September 26, 2014

Late blight Found in Cherry Tomato in Cumberland County – 9/26/14

Late blight has been found in small cherry tomato field near Roadstown, NJ today where 100% of the field is affected. This is the third report of Late blight in New Jersey this year and the first since 9/8.

Cool day and night temperatures with prolonged dews are ideal for Late blight development, especially in fields where no protectant fungicides have been applied in recent weeks.

All growers who are still in tomato production should continue to scout on a regular basis and apply protectant fungicides. Abandoned commercial fields, need to be disked under or  sprayed with gramoxone to kill all living tissue. All abandoned organic fields should be disked under or plants should be pulled and discarded.

Filed Under: Vegetable Crops Tagged With: ,
October 21, 2013

Late Blight Confirmed on Organic Tomato in South Jersey

Late blight was confirmed in an organic tomato field late last week south of Bridgeton, New Jersey. As a note, growers who are still picking tomatoes should continue to scout up until the final pick and destroy field as soon as possible once harvesting is finished either by applying gramoxone or discing under plant material. Growers with late blight issues this growing season should be especially diligent. The threat of late blight in our area will remain up until the first frost. Late blight has the potential to overwinter in our area on infested potatoes left in cull piles or unharvested tubers left in the field.

Filed Under: Organic Production Tagged With: ,