22 articles tagged "Protected Culture and Season Extension".

Figure 2. Multi-leaf lettuces grown in a high tunnel (photo credit: Liz Maynard)

Winter farmers markets are becoming more and more popular. Lettuce is a primary type of vegetables grown for the market. As we are finishing up summer crops, it is a good time to learn and refresh knowledge about lettuce. This article discusses some of the basics of growing lettuce in high tunnels, as well as the lessons we learned from a trial conducted at Southwest Purdue Ag Center in fall 2016. Lettuce Types Lettuce has multiple morphological forms major types include crisphead (iceberg), butterhead (bibb), romaine (cos), Batavian (summer crisp), and multi-leaf lettuce (salanova). The first decision about growing lettuce is whether to harvest full-size heads of lettuce, or to harvest ‘baby-leaf’ lettuce (Figure 1). These harvest methods require very different production practices. Full-size heads are harvested one time as a single head of leaves. Baby-leaf lettuce is first harvested when single leaves reach about 4 to 5 inches, and[Read More…]


Figure 3. Plant infected with bacterial wilt, transmitted by spotted and stripped cucumber beetles

In issue 619 of the Vegetable Crops Hotline newsletter I reported that during April 2016 research focusing on the development of a unique market segment for Indiana melon growers was initiated. The research aims to demonstrate that through the use of high tunnels or greenhouses growers will be able to market melons earlier and increase yield while keeping quality undeniably high. Initial research focused on variety evaluation in a soil and soilless production system in high tunnels and a greenhouse, where the plants were trellised vertically. In the long term, we aim to establish the best production practices for high tunnel and greenhouse growers in Indiana and we will do a complete life cycle analysis to determine the profitability of the proposed production systems. Well it sounds all easy to do, but in reality I have experienced several production related issues during the growing season. Let me present to you[Read More…]


Last week, the highest temperature reached 110°F for a few successive days inside of our high tunnels. As a result, we observed some blossom drop on tomatoes. More information on high temperature effects on tomato fruit set can be found here. In addition to blossom drop, high temperature and high light intensity contribute to sunscald injury, uneven ripening, and cracking of tomato fruit. To protect tomatoes from damage caused by excessive heat, we placed 30% black shade cloth on top of the high tunnel. By installing the shadecloth, we expect there will be less cracking and more uniformly ripe tomatoes. Tomato marketability will increase. However, using shade cloth also has some negative effects. In this article, we review the effects of high temperatures on tomatoes, and discuss positive and negative aspects of using a shade cloth. Excessive high temperature (above 100°F) lasting for a few hours for successive days could cause tomato flower abortion and affect[Read More…]


The cost of high tunnel and greenhouse infrastructure is high. The purchase price of high tunnels can vary between $2.00 and $7.00 per square foot, while climate controlled greenhouse costs can vary between $7.00 and $30.00 per square foot. Several factors have an impact on the costs of setting up new high tunnel or greenhouse infrastructure. Location – It is essential that the terrain selected for the construction of high tunnel and greenhouse infrastructure be well drained and level. High tunnels and greenhouses displace rainfall and provision has to be made for drainage infrastructure to redirect the water. Additionally, provision has to be made for new irrigation lines and if necessary, electricity and gas. As a general rule the distance of high tunnels and greenhouses from obstacles like trees or a building should be twice the height of that obstacle. This also applies to the distance between high tunnels or[Read More…]


Figure 1. Note stigma of tomato flower on the left was more exerted compared to flower on the right. In addition to temperatures, genetic factor, nutritional status and light might cause stigma exertion.

Maintaining temperature in the ideal range is very important for tomato fruit set. The optimum temperatures are 60-75°F (night) and 60-90°F (day). Studies showed that exposing plants to 3-h periods of temperatures above 104°F on two successive days may caused fruit set failure. Not only is the maximal temperature critical for fruit set, maintaining night temperature in the ideal range is also essential. Effects of high temperature on fruit set are primarily on the stage of pollen development, which occurs about nine days before flowers open. High temperatures also affects flower structure by causing stigma exertion that prevents pollen from successfully landing on the stigma (Figure 1). After pollination, pollen germination can be severely reduced at temperatures above 100°F. Preventing temperatures from reaching the extremely high level is important in high tunnel tomato production. Since biomass production and flower numbers are less likely to be affected by high temperatures compared to[Read More…]


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We went through an unseasonably cold period in early April (Figure 1). In southern Indiana, a few high tunnel tomato growers have already planted their crops. These plants may need some extra help. In Vincennes, IN, we used row covers to cover the newly planted tomatoes in high tunnels the past few nights, our recorded lowest temperature was 37 °F under row covers. Plants all look good. However, the temperature is apparently too cold for cucumbers. The majority of the early planted cucumbers in our high tunnels were dead. We are waiting for the weather to warm up (soil temperature at least above 60 °F) to reset the cucumbers. Please let us know if you also ran into problems in the past a few days because of the low temperature. It might be issues in the greenhouse, the high tunnels, or even the field. We would appreciate you sharing your experiences with us.      


Census data showed that in 2014 Indiana (12 acres), Illinois (11 acres) and Kentucky (13 acres) dedicated a very small portion of their food crop acreage to production under protection. According to the USDA National Agriculture Statistical Service 2014 Horticulture Specialties Census, of all the states surrounding Indiana, Ohio and Michigan have grown and sold the most food crops under protection, 24 and 25 acres, respectively. The use of high tunnels for vegetable production seems to be a novelty in the Midwest. But it can be a very important tool for every vegetable grower as it can be used to modify the growing environment for crop earliness, to protect the growing crop against environmental stress, to reduce disease and insect pressure and to extend the growing season. Covering the soil with a high tunnel prevents natural rainfall from washing or leaching nutrients and soluble salts from the soil, can lead[Read More…]


A grafted tomato plant growing in a high tunnel. (Photo by Wenjing Guan)

​You might have heard about tomato grafting, or you might even already have tried the new technique. Yes, it has multiple benefits: control of soilborne diseases, enhanced tolerance to abiotic stresses, and increased productivity. It works for some growers, but not all. Why? There are several reasons. First, effects of grafting on controlling soilborne diseases depend on the presence of the disease that the rootstock is designed to control. For example, grafting might not be very helpful for white mold, because current commercial rootstocks do not have resistance to white mold. However, grafting might work if the primary problem is Fusarium crown and root rot, as most commercial tomato rootstocks have resistance to this disease. With that said, it is very important to look at the disease resistance profile before deciding on the rootstocks. Second, grafting effects on improving yield depend on factors such as scion and rootstock cultivars, cultural[Read More…]


(Photo by Shubin K. Saha)

​Tomato growers who utilize high tunnels to reach early markets often find that there are few economic alternatives to tomato. Therefore, many growers grow tomatoes after tomatoes instead of rotating to a different crop. The repeated cropping of tomato in the same area can lead to disease problems such as Fusarium crown rot and white mold (timber rot). Soil solarization takes advantage of solar radiation to heat the soil to temperatures that are lethal to many fungal pathogens, nematodes, and weed seeds. In Indiana, soil solarization is not always practical for field use since the period where soil solarization would be useful, summer, is also the period where most growers must produce crops. The use of soil solarization in high tunnels, however, may be more practical since these crops are produced earlier than field crops. Additionally there is chance for greater heating of the soil if the high tunnel vents[Read More…]


(Photo by Dan Egel)

​We have received a number of reports of outbreaks of spider mites, primarily in watermelons and in high tunnels. The problems in high tunnels are not unexpected because one of the primary causes of mortality in mite populations is rainfall washing them off the plants and, of course, that is lacking completely in high tunnels. With all the rain we have had, it’s a little surprising that we are seeing problems in watermelons, but the older I get, the less I’m surprised by how infrequently arthropods behave the way we expect them to. In both scenarios, we don’t really have treatment thresholds for mites. Generally speaking, if populations are increasing, they need to be controlled. Once the decision to treat has been made, that’s where things get very different. In watermelons, we have a variety of pesticide choices. See page 115 of the Midwest Vegetable Production Guide (ID56) for the[Read More…]


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