Posts Tagged ‘high tunnel’

Managing Diseases of High Tunnel Tomatoes

Friday, June 1st, 2012

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

I have received several questions about timber rot caused by Sclerotinia sclerotiorum, leaf mold caused by Fulvia fulva, and gray mold caused by Botrytis cinerea over the past week for greenhouse and high tunnel tomatoes in Maryland and Delaware.

Timber rot is common where tomatoes (or another susceptible host) have been planted in ground beds in the past. The fungus Sclerotinia sclerotiorum causes disease on hundreds of plant species. Therefore rotation is difficult. Even when a high tunnel is moved between seasons, the disease can be severe because the fungus overwinters both in and around the tunnels. Usually the primary source of inoculum is outside of a high tunnel. In the spring when the soil is moist, the fungal fruiting bodies emerge and spores (ascospores) are released. These ascospores will be released continually throughout the spring and are carried on wind into the doors or raised sides of nearby high tunnels. Ascospores are usually carried or dispersed less than 330 feet. Therefore it is important to use sanitation within 330 feet of a high tunnel. No plants, leaf clippings, potting mix, or soil from the tunnels should be discarded within this area.

There are some practices that will help reduce timber rot pressure, such as minimizing the length of time that the soil stays wet. The biocontrol, Contans has been effective in managing Sclerotinia diseases in the field. Contans, which is a formulation of the fungus Coniothyrium minitans, parasitizes the survival structures of S. sclerotiorum. If it is sprayed on the area around the high tunnel and watered into the soil, it may help reduce ascospore formation in future years. Because the product is a live organism, it must be handled carefully to preserve its effectiveness. Contans would be a good choice for fields or areas around high tunnels, which are used repeatedly for a susceptible crop. See the Contans label for additional information. Other products labeled for Sclerotinia timber rot are Endura, which is labeled for field use, and Botran, which is labeled for greenhouse use.

Leaf mold and gray mold are both favored by high humidity and therefore improving air flow can reduce the extent of disease spread. There are several fungicides that are labeled for greenhouse use that will help reduce disease. These include Scala for leaf mold, Mycostop and Decree for suppressing gray mold, mancozeb products such as Dithane F-45, and copper. In addition to timber rot, Botran has activity on gray mold.

Construction and Management Considerations Important For High Tunnel Success

Thursday, April 12th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

There have been many high tunnels that have gone up recently on vegetable farms, partly due to available cost share programs.

High tunnels require proper set up and then daily management for crops to perform well in them.

Considerations include:

Site selection: A tunnel site should have good soil, flat but with drainage away from the interior (for rainwater off of the cover), with no shading from trees. Protection from heavy winds can be valuable but ventilation (air cross flow when side curtains are open) should not be significantly impeded.

Soil management: Because it is a small area to be used intensively and is usually set in place and not moved, consideration should be given to improving soils and correcting soil problems prior to erecting the tunnel such as adding compost to increase organic matter and improve soil health.

Cover selection and cover management: Single or multiyear covers, thickness, single or double sheets, tightness, and strapping for minizing wind effects are all considerations. Shade covers for summer production should also be considered.

Side curtain design and operation: This is one of the most critical parts of the high tunnel. Side curtains should be designed for ease of opening and closing and the ability to partially open. They will be opened and closed daily or even several times a day so ease of operation is critical.

End walls and door design and management: If compact tractors are to be used to establish beds than end doors must be designed to allow access. End doors are also a part of the ventilation and should be designed as such for easy opening and closing and partial opening and closing

Ventilation management: Ventilation management is a critical part of high tunnels. Venting is necessary to manage temperatures and allow for removal of excess heat, reduction of humidity in houses, and for wind movement for crops like tomatoes that require wind for pollen movement and fruit set. Side curtains and end walls need to be opened at the correct times and closed prior to temperature drops to accumulate heat for the night. Prevailing winds need to be considered.

Heat accumulation and managing for freezes: This includes decisions on when to keep houses tight and accumulate the maximum heat during the day, when to close curtains, the use of row covers in the tunnel for freeze protection the use of heat sinks to store and release heat, and other heat accumulation and freeze protection techniques. This needs to be tailored to the specific crops being grown

Beds and walkways: Bed formation, bed management, and walkway management should all be set up to maximize root performance, minimize compaction and facilitate maintenance and harvest. Use of permanent beds or box beds, raised beds, flat ground production all are options. One key is to maintain the same walkway areas each year to limit compaction to dedicated areas.

Mulching, ground cover, and weed management: Choice of plastic mulch, landscape fabric, or natural mulches will affect earliness and weed control.

Irrigation choice and management: Drip irrigation, microsprinklers, and hand watering are all options. The key is to take advantage of the ability to control water without the effects of heavy rainfall. This should be tailored for the different crops – drip irrigation for tomatoes, microsprinklers for greens beds, and hand watering for baby greens for example.

Disease management: While most foliar diseases are reduced in high tunnels, there can be a build-up of soilborne diseases if rotations are limited.

Insect and mite management: Tunnels often see an increase in mite problems and different insect profiles than outdoor production.

Crop choice, rotation and seasonality: Almost anything can be grown in a tunnel, including vegetables, cut flowers, small fruits, and even dwarf tree fruits. The key is to match your production and markets with what is most profitable for the limited tunnel area. What will make the most money per square foot per month? Also consider rotations to avoid disease buildup.

Tomato Pinworms Can be a Problem for Greenhouse Growers

Thursday, April 5th, 2012

Cory Whaley, Sussex Co. Extension Ag Agent; whaley@udel.edu and Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Tomato pinworms have recently been found infesting tomatoes in a greenhouse in Delaware. According to Jerry Ghidiu, an entomologist with Rutgers University, once pinworms become established they can move quickly through the house and threaten the entire crop. He stated that tomato pinworm is difficult to control and it is best to catch it early; multiple applications of insecticides will be needed for control. First instars are foliar feeders and mine into the leaf. Older larvae may fold the leaf over itself, or stick leaves together. In severe infestations all leaves are infested and the crop may have a burnt appearance. Larvae can then move into the fruit, making control much more difficult. Larvae will leave small pinholes at entry points. Pinworm can complete its life cycle in 28 days and there may be more than 7-8 generations per year. Adults are small gray moths and once adults are seen, infestations are severe. Pheromone traps can be used to detect and monitor the moths.

Entomologists in the region recommended Pylon as the best control labeled for greenhouse tomato use to control this pest. They also noted Entrust as another material to consider especially for organic production; however, it carries the following restriction: “Do not apply to seedling fruiting vegetables (which includes tomatoes) and okra grown for transplant within a greenhouse, shade house, or field plot.” As with all materials, you need to read the label for rates and restrictions before applying. Please refer to the Commercial Vegetable Production Recommendations for additional products to use in a rotation.

 Tomato pinworm larva

 Tomato pinworm larva on a damaged leaf

Tomato pinworm frass and leaf damage

Burnt appearance and leaf folding caused by tomato pinworm feeding

Avoiding Failures with Early Planted Vegetables

Thursday, April 5th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

The mild weather has many growers eager to get an early start with summer vegetables. Early markets are often the most profitable with higher prices. However, growers should proceed with caution and realize that failures can occur if cold sensitive vegetables are planted when temperatures are sub-optimal. As we get back to more seasonable weather in April, there will be many nights ahead with temperatures in the 30s and frosts and freezes are still a concern.

Each vegetable crop has a minimal temperature at which growth will occur. Our summer vegetables such as tomatoes, peppers, cucumbers, watermelons, and squash simply do not grow if temperatures are in the 40s or 50s. Squash and cucumbers do not put on growth with temperatures below 60°F, cantaloupes, watermelons, tomatoes, peppers, and eggplants will not put on growth with temperatures below 65°F. If temperatures are below these minimums, plants will just “sit still” and will be at risk of cold injury, wind injury, and damage from early season insects and diseases. Cold soils will limit root growth, further placing plants at risk due to inadequate water uptake and the risk of desiccation. Excess cold can also stunt some summer vegetables so that they do not fully recover. This is especially true of cantaloupes.

When planting summer vegetables early, growers need to consider all the tools available to maximize heat accumulation and minimize heat loss. The following is a list of these tools:

  • · Use raised beds or ridges. Ridges that are oriented east-west with crops planted on the south side, will benefit from the additional heat accumulation from the increased solar radiation on that side. Sandy soils heat up quicker due to lower water content.
  • · Use planted windbreaks, most commonly rye, between beds or rows. Windbreaks reduce heat loss from cold winds and help to accumulate heat. Rye reaches full height by the end of April on most of Delmarva. Cold winds are the most damaging to summer crops. Sand blasting during dry wind storms can actually cut plants off at the soil level. Growers doing field plantings for early crops in unprotected areas should always use windbreaks.
  • · For direct seeded crops, choose cold tolerant varieties, plant shallower and into well drained soils, and choose protected fields for earliest plantings. Also till soils well ahead of plantings to allow for them to heat up. Plant as soon as soil temperatures are adequate for germination. Also choose seed that has high quality and performs well in a cold germination test.
  • · To warm the soil more quickly, use plastic mulches. Plastic mulches increase soil temperature and help hold heat during night periods. They can increase soil temperatures 5-20 F° depending on mulch color. In order of lowest to highest heat accumulation Black < Red < Blue < Olive/Brown < Clear in selecting mulches. Mulches should be laid tight on a firm moist bed that is clod free. This will allow for more effective heat transfer and accumulation. Loose plastic and cloddy soils will reduce plastic mulch benefits.
  • · Use clear poly plastic covers. Most commonly, these come with slits or perforations to vent excess heat. They can be placed over direct seeded or transplanted crops with wire hoop supports (low tunnels) or they can be placed over ridges with transplants or seeds planted in the depression between the ridges. Zip tunnels and vented systems, where clear plastic can be easily closed and opened, have also been used. High tunnels also use poly plastic for protection and heat accumulation. I will discuss high tunnel management further in additional articles.
  • · Use spun bond poly or woven poly floating row covers to insulate, frost protect, reduce wind, reduce heat loss from soils and beds, and accumulate some heat. They can be placed directly over low growing crops such as strawberries or can be used with wire supports for other crops. The insulation they provide can protect 2-8 F° depending on thickness. Usually a 0.9-1.2 oz. cover is used to provide protection but not limit light too much.
  • · For smaller plantings, use of additional heat sinks to absorb heat during the day and then release it at night can promote earliness. Heat collection devices are usually filled with water and may be clear or black plastic containers or tubes.

Combinations of these practices will provide greater cold protection, heat accumulation, and earliness. This could include plastic mulch + row cover, plastic mulch + clear row cover + floating row cover, plastic mulch + row cover + heat sink, plastic mulch + clear row cover + floating row cover + heat sink. Use of these combinations in a high tunnel will further enhance success with early planted summer vegetables.

Strawberry Planting Season

Friday, September 9th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Planting season is here for plasticulture strawberry systems. In our area, most strawberries are planted using plugs produced by rooting tips. While plugs are more forgiving than bare root plants, actions prior to planting and at planting still can affect future performance. The goal is to have quick, uniform rooting across all plants on the bed so that proper sized crowns are produced before going into winter.

The first key is to have a firm, high, uniform raised bed with black plastic mulch tight against the soil. This allows heat to transfer to the soil, warming the root zone, and promoting fall growth. Loose plastic will not do this.

Liming should be done ahead of time if necessary to raise pH and provide Ca and Mg if necessary. Base fertilizer should be applied to the bed before formation to provide necessary P and K and adequate but not excessive N for fall growth (60-75 lbs N is recommended at bedding).

Whether you are planting by hand using a dibber to make holes or are using a water wheel transplanter, uniform planting depth is critical. Workers placing plugs should be trained to place plants so that crowns are not buried or are not above soil level. If buried, crowns will be susceptible to rots and plants may die or be stunted. Buried buds may not be able to leaf out. If planted too shallow, plugs will be susceptible to drying out before being able to root. In addition, during planting, workers should not plant weak, diseased, or damaged plants

Water is also critical during establishment. While we are having a spell of rainy weather, you cannot always count on rain during the establishment period. Drip irrigation should be run to wet the bed. However, this is usually not enough. Plants should receive water at transplanting in the hole and should also be watered overhead during the establishment period for best results.

Planting date is critical for plasticulture systems. While row cover management can be used to control growth, planting at the proper date will make row cover management in the fall much simpler. The ideal planting window is the first half of September, prior to September 20, for most areas in our region. Strawberries planted in this window should produce adequate numbers of branch crowns in the fall period and can then be covered in late November or early December for winter protection.

Later plantings (after September 20) will require earlier row covering to trap some heat and put on adequate fall growth.

In high tunnels, the planting window in the fall will be wider because of the extra heat provided and later plantings can be successful. However, some earliness will be lost.

Summer Vegetable Plantings for Fall Harvest

Thursday, July 28th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Plantings for fall harvested vegetables are underway. Timing these plantings can be a challenge, especially where multiple harvests are needed. Plantings from mid-July through the end of August may be made, with cutoff dates depending on the crop, variety, and season extension methods such as row covers, low tunnels, and high tunnels.

These plantings can be divided into 2 groups: 1) warm season vegetables for harvest up to a killing frost and 2) cool season vegetables for extended harvest in the fall.

The three main factors influencing crop growth and performance in the fall are daylength, heat units, and frost or freeze events. A few days difference in planting date this time of year can make a big difference in days to maturity in the fall.

Warm season vegetables for fall harvest include snap beans, squash, and cucumbers. July plantings of sweet corn can also be successful to extend seasons for farm stands. Mid-July plantings of tomatoes and peppers also are made for late harvests, particularly in high tunnels.

Cool season vegetables for fall harvest include cabbage, broccoli, and cauliflower; the cole crop greens, kale and collards; mustard and turnip greens; turnips for roots; spinach; beets; lettuce; leeks; green onions; and radishes.

To extend harvest in the fall, successive plantings are an option. However, days between plantings will need to be compressed. One day difference in early August planting for a crop like beans can mean a difference of several days in harvest date.

Another option to extend harvest in the fall is with planting different maturing varieties at the same time. This is particularly successful with crops such as broccoli and cabbage where maturity differences of more than 30 days can be found between varieties.

Another way to get later harvests is by use of row covers or protecting structures. This can allow for more heat accumulation and will aid with protection against frost and freezes. Decisions on what type or combination of covers/protection to use and when to apply the protection will influence fall vegetable maturation and duration of harvest.

A final factor for summer planting for fall production is on planting cutoff dates. For example, a crop such as cucumber may produce well with an August 2 planting but poorly with an August 8 planting; broccoli has a wider planting window than cauliflower; turnip greens have a wider planting window than kale.

Bolting in Spring-Planted Vegetables

Friday, May 20th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Bolting is the term used for flower stalk formation in vegetables. Bolting response may be related to temperature, daylength, or a combination.

Bolting in spinach, lettuce, and some radishes (oriental types) will occur naturally as days get longer. High temperatures will accelerate bolting in spinach and lettuce.

Many mustard family plants need a cold period along with lengthening days to flower. The amount of cold needed depends on the species and variety. Mustards are very prone to cold initiated spring bolting; turnips, Chinese cabbage, and salad radishes require more cold to initiate the bolting response.

In the cole crop group, cabbage planted very early in cold springs may bolt and premature flowering in broccoli, cauliflower, kale, and collards also occurs when planted too early, or if the spring is abnormally cold. However, cole crop transplants have to be of a certain age to be susceptible to this cold-initiated bolting.

Other biennial vegetables such as beets, carrots, and onions also can be induced to bolt but only once plants have reached a certain size (they are past the juvenile growth stage). This is uncommon in our region.

Controlling bolting starts with planting during the recommended planting window. Early planting will contribute to bolting in some crops (such as cabbage), late planting in others (such as lettuce).

Select varieties that are adapted to the spring planting season (an example would be Savannah mustard). Chose slow bolting varieties of spinach and lettuce. Choose spring adapted varieties of oriental radishes and Chinese cabbage.

One issue that complicates this is the use of high tunnels for early production. High tunnels allow for earlier planting but cold snaps still may drop temperatures enough to cause the cold induced flowering response in many of these crops.

 

Tomato Spotted Wilt Problems in High Tunnel/Greenhouse Tomatoes

Friday, May 6th, 2011

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

I recently visited a grower that grows both tomatoes and bedding plants. The plants are grown in a high tunnel-like setting, i.e., with heat. The grower was having problems in his tomato plants, but not in his bedding plants. The tomato plants looked like they had tomato spotted wilt virus (TSWV). The symptoms were found on most of his tomato plants, which would be unusual, as most of the time only an occassional plant here and there would be infected with the virus. The grower thought that is what he had as did an alert County Educator—and they were right. The grower unfortunaetly had a perfect storm in his operations that produced high percentages of TSWV infection in his tomato crop, but not his bedding plants.

Tomato spotted wilt virus is an obligate parasite; it must have a living host and must be moved from one plant to another by thrips or through cuttings or possibly seed. TSWV is transmitted most efficiently by Western flower thrips (WFT) (Frankliniella occidentalis), and less so by Onion thrips (Thrips tabaci), Tobacco thrips (Frankliniella fusca) and a few other thrips species. It is not transmitted by Eastern flower thrips (Frankliniella tritici).

WFT completes its life cycle in about 10-18 days. Eggs are laid in the leaf or tomato fruit. When WFT oviposit into tomato fruit they often cause a deeper dimple (black arrows Fig. 1) than other thrips species and very often the dimple is surrounded by a halo of white tomato tissue (white arrow Fig 1). This is how I could tell the grower had WFT present at one time (when I visited I could find no live thrips) at fairly high levels by the ovipositioning marks on his tomatoes. Larvae hatch in about three days and immediately begin to feed and in so doing pick up the virus. After four days, they pupate in the soil, and in a little over three days, the pupae become adults. Only immature thrips can acquire the virus, which they can acquire within 15 minutes of feeding, but adults are just about the only stage able to transmit the virus. Adults can transmit the virus for weeks.

TSWV infected leaves may show small, dark-brown spots (Fig. 2) or streaks on stems and leaf petioles (we found one prickly lettuce weed with such a symptom). Growing tips are usually affected with systemic necrosis and potentially stunted growth. Tomato fruit will have mottled, light green or yellow rings usually with raised centers (Fig 3).

Weed hosts function as important virus reservoirs for TSWV and can survive in and around greenhouses or even high tunnels through the winter. Some of these weeds include prickly lettuce, chickweed, (Fig. 4) spiny amaranth, lambquarters, black nightshade, shepherd’s purse, galinsoga and burdock. This grower unfortunately had a good crop of prickly lettuce at one end of his high tunnel.

The grower had been able to control his thrips populations with spinosad, but western flower thrips are notorious for developing resistance and sure enough have developed resistance to this insecticide in many greenhouses. So populations of WFT increased and with the weeds that were around and in the high tunnel some of which tested positive for TSWV, but negative for INSV, it was a perfect scenario for an outbreak of TSWV. I should note here that we tested for both INSV and TSWV on the tomatoes, weeds and impatiens. Only TSWV was found in the tomato and the weeds. No INSV was found in any sample. Although both viruses are transmitted by the same thrips species these viruses tend to infect either bedding plants (INSV) or tomato/pepper plants (TSWV). The grower threw out all his infected tomato plants and is in the process of killing his weeds in and around his high tunnel. He was able to get control of his thrips in his bedding plants using combinations of pylon and pyrethroids. One variety of tomato the grower was growing that did not show any symptoms of TSWV, even though it was right next to the other infected varieties was Mountain Glory.

Fig 1 Tomato fruit with WFT ovipostion marks

Fig. 2 Tomato leaves with TSWV symptoms and positive immunostrip (two black arrows; Agdia, Inc)

Fig. 3 Tomato fruit with TSWV symptoms

 

Fig. 4 Two common weed hosts of TSWV; prickly lettuce and chickweed

 

Thrips on Winter Annuals

Thursday, April 14th, 2011

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

Vegetable and bramble growers in Maryland have called me often over the last couple of years about fruit problems in their fields possibly caused by thrips. As an overall study of the possible impact thrips may be having on vegetable and fruit quality I have been conducting surveys for their numbers and species. I have taken weed samples throughout the winter and early spring from vegetable fields and high tunnels looking to see if any thrips were overwintering and if so what species they were. Below is a 9-point summary of the sampling program.

1.  For most samples very few thrips were found.

2.  In 14 of the 20 sample sites thrips were found in December through January on winter annuals.

3.  At 9 sample sites thrips were found in March.

4.  The worse sample sites were high tunnels that had chickweed and/or henbit winter annuals growing along the outer or inner edge of the base of the high tunnel (Fig 1). 87% of the sampled winter annual weeds at these sites over the last two years had at least 3 female thrips (one sample had 23 female thrips).

5.  Of the total thrips found 76% were female adults, 19% were males and 5% were immatures or pupae.

6.  Western flower thrips were found to overwinter in Maryland, Delaware, SE Pennsylvania and NE Virginia, although only in low numbers (Fig 2).

7.  Chickweed was found to harbor 66% of all thrips with wild mustards and henbit being the next best winter hosts.

8.  Sampling-sites near high tunnels or woods had a greater probability of containing thrips than sites out in a field.

9.  Farms where thrips were found to overwinter had greater probabilities of infestations during the season.

Even though several thrips species, including Western flower thrips, were found to overwinter in the mid-Atlantic area it does not mean we have a thrips problem. However, growers do need to watch for any early season infestations in their field and high tunnel brambles and not overreact by spraying an insecticide unless really needed. Most brambles can have at least 5 thrips or more per fruit/flower before there is any possibility of damage. The species of thrips you have should be determined only if you think thrips are causing fruit quality problems at low densities. I would be glad to look at your thrips if you send them to me: 2005 Largo Rd, Upper Marlboro, MD 20774 or you can call 301-627-8440 or email me: jbrust@umd.edu.

Figure 1. Winter annual weeds along outside (under snow) and inside border of high tunnel

Figure 2. The proportion of thrips species found to overwinter at the 20 sample sites

 

Timber Rot, White Mold, Sclerotinia Rot in Spring Greenhouses and High Tunnels

Thursday, May 6th, 2010

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

The fungus Sclerotinia sclerotiorum along with other Sclerotinia spp. cause disease on hundreds of plant species, including most vegetables. Diseases caused by Sclerotinia, such as timber rot or Sclerotinia rot are becoming very serious problems in vegetables grown in greenhouses and high tunnels. The diseases overwinter in the soil as large resistant sclerotia, which multiply during years of susceptible crop production. However, even when a high tunnel is moved between seasons, the disease can be severe because the fungus overwinters both in and around the greenhouses and tunnels. The primary source of inoculum may originate inside as well as outside these structures. In the spring when the soil is moist, the fungal fruiting bodies emerge and spores (ascospores) are released. These ascospores will be released continually throughout the spring and are carried throughout the house if originating inside the structure. If the ascospores originate outside the house, they are carried on wind through the doors, vents or raised sides of nearby structures. Ascospores are usually carried or dispersed less than 330 feet. Therefore, it is especially important to use sanitation within 330 feet of a greenhouse or high tunnel. No plants, leaf clippings, potting mix, or soil from the greenhouse or high tunnel should be discarded within this area.

Inside the greenhouse or high tunnel, improve air flow in and around the plants by increasing in-row spacing and trellising plants to reduce disease incidence. Conversely, the proliferation of leaves near the soil will increases disease. The biocontrol Contans has been effective in managing Sclerotinia diseases in the field. The active ingredient of Contans, Coniothyrium minitans, parasitizes the overwintering (or surviving) sclerotia. If Contans is sprayed on the area around the high tunnel and watered into the soil, it may help reduce ascospore formation in future years. Contans must sprayed long before disease development occurs (2 months) to be effective within a crop year. Because the product is living, handle it carefully prior to use. Contans would be a good choice to try in fields or areas around greenhouses and high tunnels that are used repeatedly for a susceptible crop. See the Contans label for additional information.

Other fungicide products labeled for Sclerotinia in the greenhouse are Botran and Terraclor. Maximizing fungicide coverage to plants during application is important. Apply fungicides prior to disease development for greatest efficacy. Keep in mind that the fungus becomes established on senescing tissue first and then colonizes the plant. See the Botran and Terraclor labels for information on individual vegetable crops.

The black sclerotina on the small tomato fruit will overwinter and result in ascospore formation in future years. The fruit should be either buried or discarded more that 330 feet from the high tunnel.