Wednesday, May 23, 2012

High Tunnel Crop Talk Notes 05-21-2012

Summary: Crops are progressing well with small fruit harvest underway, cukes close to harvest, tomato and pepper fruit developing. Tomato pith necrosis has been observed.

Join us again on June 4, 2012. 12:30–1:30 p.m. Eastern/11:30-12:30 Central. Point your web browser to and click on the phone icon to be dialed in to the call, or just dial 1-866-492-6283.

Tomato pith necrosis
Tomato pith necrosis often causes the pith to appear rotten and the external stem to have necrotic lesions.  Photo by Dan Egel.
Tomato pith necrosis
The stems of tomato plants affected by tomato pith necrosis often appear shriveled and wrinkled. Photo by Dan Egel.
Tomato Pith Necrosis:
Tomato pith necrosis has been observed recently in a high tunnel.  This disease is caused by a bacterium.   Although observations of this disease in Indiana are infrequent, growers should scout their production for tomato pith necrosis.  Management options include avoiding excessive nitrogen fertilization and high humidity.

If Indiana growers see suspected tomato pith necrosis, Dan Egel recommends that you send a sample in to the Purdue Plant and Pest Diagnostic Lab, or to him, for confirmation of the diagnosis, and so that pathologists can document how common the problem is. It would be a good idea to rogue out symptomatic plants and a few nearby, and destroy them away from the greenhouse. Crop rotation away from tomatoes is recommended. If rotation is not possible, then Egel recommends using a landscape fabric ground cover, cleaning it between crops, and taking all tomato plant material out and away from the high tunnel after the growing season.


Wabash County: It is very dry, just a teaser of rain last night.

Southwest Indiana: Harvest of raspberries in tunnels is underway. An unknown problem was observed: black sticky substance on the surface of the berry. (See picture below). Any suggestions of what this could be?
Raspberry fruit with black sticky substance.
Raspberry fruit with unidentified black sticky substance. Photo by Dan Egel.

South Central Indiana: Received an NRCS grant for a high tunnel and plan to put it up this year. Have in the past done a lot of greens in a smaller tunnel, 20ft x 20ft 6ft high. The spinach crop is still going from plantings as early as last September and late as February as well as turnip greens and winter lettuces. Thinking of doing a few figs and berries in the new tunnel.

North Central Indiana: Tomatoes in high tunnels have dime-size fruit. Pepper plants just starting to set fruit. Harvesting a small planting of everbearing strawberries which were put in to see how they would do.

Central Indiana, Meigs Research Farm at Purdue: Tomato variety trial transplanted abaout two weeks ago in three tunnels. Peppers in a nutrient research project (see March 26 HTCT notes for more information) transplanted into a tunnel about the same time. Cover crops in the tunnel had to be worked in before planting the peppers.

Northeast Indiana: Under an acre of Haygrove tunnels, producer has tomatoes (both red slicers and romas) at first fruit set, peppers close to first fruit set, and self-pollinating slicing cucumbers that will be ready for harvest next week.


High tunnel manufacturers:
Tunnels represented on the call include Rimol, FarmTek, Haygrove, and one from R&M Produce Supply in Goshen, IN. The Haygrove owner chose that type because he had an opportunity to purchase them used and could split cost with others. Also, he was familiar with them on neighboring farms. The tunnel from the supplier in Goshen was reasonably priced; note that buyer arranges transport. The FarmTek tunnels at the Purdue Meigs farm are the economy quonset model; Tristand Tucker who works there would recommend one of the sturdier models rather than the economy model. He would also recommend a bow spacing of 4 ft., or maybe 6 ft., but no wider, and a tunnel with higher sidewalls so it is easier to work close to the edge. The tunnels at Meigs came with the zippered fabric endwalls; those have been replaced with hard double-layer plastic. A gothic arch tunnel with a steeper pitch sheds snow better than a quonset tunnel which has a rounded arch. The Rimol tunnels at SW Purdue Ag Center and under construction at Pinney-Purdue are gothic arch tunnels. The tunnels at SW have high sidewalls and a roof vent; the tunnels at Pinney will have 4-ft. side walls and be on rails to they can be moved to cover a different section of soil.

What about double-layer poly?
Double layer poly has better insulating value but reduces light inside the tunnel. It is common on greenhouses used for bedding plant and other spring plant production, including vegetable transplants. At Pinney-Purdue a double-poly covered greenhouse has been used for transplant production, and has worked well. A small fan blows air between the layers to keep it inflated. There are straps over the greenhouse to stabilize the plastic - but not every double poly house has these. Air to inflate between the plastic layers is drawn from outside the greenhouse. If drawn from inside the greenhouse it will have more moisture in it, and condensation between layers of plastic may be a problem.

How do people stake peppers in tunnels?
Three methods were mentioned. One method works when peppers are grown in a double row on a bed. Stakes are placed along each edge of the bed. Twine is tied horizontally between stakes at a height that will support pepper plants to prevent them from falling sideways over the bed edges. The photo below shows another method: tall posts along each side of the bed support a horizontal string above the plants. Hanging down from that horizontal string are strings to which pepper plants are attached. Peppers can also be supported using the stake and weave system likes tomatoes. It would be great to have some more photos and descriptions of these or other methods for staking peppers.
Staked pepper plants.
Staked pepper plants is a high tunnel. Photo by Dan Egel.
Notes by L. Maynard. Please get in touch with corrections or additions, or just post a comment.

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