38 articles tagged "Greenhouses & High Tunnels".

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Screening can be an effective measure to exclude unwanted pests from colonizing your crops. In high tunnels, one of the biggest challenges to successfully implementing exclusion screening is managing the unintended side effect: reduced airflow. In spring we are clamoring to get inside the warmth that high tunnels provide, but by mid-summer they can become one of the most dreaded environments to work in. The temperatures inside high tunnels beyond mid-June can quickly exceed those suitable to plant growth. The key to maintaining crop production during this time is proper ventilation. Therefore, selecting an insect screen that will effectively exclude pests while minimizing reductions in airflow is crucial. We have been investigating the ability of such screens to keep biological control agents in and cucumber beetles out while maintaining a suitable growing environment for cucumbers, tomatoes and melons. We have looked at three different insect screen sizes over the past[Read More…]


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There are several potential benefits of growing grafted tomatoes, particularly for early season tomato production in greenhouses or high tunnels. If you are interested in trying this technique but wondering whether it is possible to graft tomato plants by yourself, a Purdue extension publication, Techniques for Tomato Grafting, (https://extension.purdue.edu/extmedia/HO/HO-260-W.pdf ) provides a step-by-step guideline for small growers to explore this technique. A question I am often asked is: when should I start to plant the seeds to produce grafted plants? The chart below shows a general timeline and materials needed for producing grafted tomatoes on a small scale on your farm. As a general rule, the grafting process delays seedling growth for 6-7 days. The delay normally does not make a noticeable difference on the size of seedlings after the grafted plants are grown in a greenhouse for more than 2 weeks prior to transplant. As a matter of fact, grafted[Read More…]


These tomato plants are exhibiting epinasty or a downward growth of the leaves in response to ethylene produced from a malfunctioning heater in a greenhouse. The topmost leaves are growing normally because the plants were removed to a separate greenhouse after exposure to ethylene. (Photo by Dan Egel).

Almost every year, I have a greenhouse tomato grower or two call me about tomato plants that are distorted and don’t seem to be growing right. The problem often turns out to be ethylene damage. This year, I have decided to write an article about it before I get those calls. Tomato plants with ethylene damage often have leaves that are curled down and stems that are twisted (Figure 1). Stems or leaves that are curled downwards are said to have epinasty (in botanical terms). Epinasty is a common symptom of ethylene damage. Ethylene is a common by-product of incomplete combustion of several different types of fuel. Incomplete combustion is often the result of heaters that are not working efficiently. Tomatoes are very sensitive to ethylene damage; however, other crops may also show ethylene damage. The tomato plants in figure 1 also have yellow seed leaves. Ethylene damage does not include yellowing.[Read More…]


Figure 2. Older leaves were pruned on cucumber plants.

Tomato is considered one of the most profitable crops grown in high tunnels, but continually growing one single crop leads to build-up of diseases. In addition, growers are facing more competition in selling tomatoes in the market. To enhance resilience of high tunnel system and increase access to consumers, crop diversification is important. In this article, instead of discussing tomatoes, we will focus on another high-value crop, seedless cucumber. Fresh consumed seedless cucumber is a popular crop in local food markets. It sells at a premium price in early seasons as does tomato. Seedless cucumbers grown under protected cultures are parthenocarpic, which do not require pollination. In addition, the climbing habit allows trellising, which maximizes the use of vertical spaces, making seedless cucumber an ideal crop for high tunnel production. Parthenocarpic cucumbers are available in different types. The long ones are often referred to as European, Japanese or English cucumbers. They have thin skins with longitudinal[Read More…]


Figure 1. Aphids on kale crop. Photos courtesy Liz Maynard.

Aphids can be one of the most damaging and hard to control pests during the winter months in high tunnels. The first step to managing aphids is to develop a scouting plan. Aphids reproduce clonally and develop quickly leading to very large population build-up in a short period of time. Therefore scouting is recommended at least three times a week. When examining plants be sure to look at the growing point and underside of leaves, where aphids prefer to colonize (Figure 1). Outbreaks commonly begin on the outer rows or the start of the row so these are places to be sure to include when scouting. In the summer months, successful control has been achieved using a soap/mineral oil spray consisting of 1.5% castile soap and 0.25% mineral oil. Cornell University also reports grower success using the biopesticides Mycotrol O and BotaniGard. These are commercially available formulations of the aphid-attacking[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…]


Figure 5: Tirreno, an Italian netted variety, orange flesh color

Indiana is a very important player in the domestic melon market. The total acreage planted in Indiana peaked in 1997 at 3,600 acres. In that year the total production was 455,000 cwt with an average income of $16.00 per cwt. The total farm value of production was $7,280,000 ($2,022 per acre). Yield has increased since 1997 from 130 cwt per acre to more than 200 cwt per acre in 2014. The Indiana melon growers have lost a significant share of the melon market since the 2011 and 2012 food borne illness outbreaks. Compared to 2011, the acreage planted and production in 2015 decreased by 900 acres and 52% (300,000 cwt), respectively. Quick Facts about Indiana Cantaloupe Transplant Production: March/April Planting Season: April – June Harvest Season: June – Sept. Plant Population (2.5 ft. x 6 ft.): 2,904 plants per acre Total acres planted: 2,100 acres (2013), 1,900 acres (2014), 1,800[Read More…]


Figure 1. A 30% black shade cloth was added to one of the high tunnels

We have discussed the pros and cons of using shade cloth for growing high tunnel tomatoes in this article https://vegcropshotline.org/article/whether-to-put-shade-cloth-on-high-tunnel-tomatoes/ Shade cloth helps with reducing temperatures inside the high tunnel. But it also reduces light intensity that is essential for photosynthesis. To better understand to what extent can temperature and light reduced with a shade cloth applied on top of a high tunnel, We did a comparison this summer at Southwest Purdue Agricultural Center, Vincennes, IN, with one high tunnel applied with 30% black shade cloth, and the adjacent one did not (Figure 1). The following figures (Figure 2 and 3) illustrate how temperature and light levels in the high tunnel were affected by the shade cloth in a typical sunny (July 23) and a cloudy day (July 2). On both days, about 10 degree difference of maximal temperatures were observed between the two tunnels. On the sunny day of July[Read More…]


Figure 2. Cowpea was worked into the soil

We have grown strawberries from Aug, 2015 to May, 2016 in one of our high tunnels at Southwest Purdue Agricultural Center. After taking the strawberry plants out of the high tunnel in the end of May, we did have enough time to grow a warm-season crop, like cucumbers. However, because for most of us June is such a busy time working in the field, we decided to put cover crops inside the high tunnel in the summer months and plant cool-season crops in the fall. Our primary goal of growing cover crops is to provide nitrogen for the following crops and increase soil organic matter. We decided to use a legume cover crop cowpea in this case because it has excellent drought and heat tolerance. Cowpea at a rate of 100 lbs per acre was sowed on June 17th. With the high temperatures inside the high tunnel, cowpea reached 30’’ high[Read More…]


Figure 1. Strawberries grown inside a high tunnel at Southwest Purdue Agricultural Center. Photo was taken on April 16 2016.

We are familiar with strawberries grown as a perennial crop in Indiana. Bare root strawberry plants are set in the spring. Fruit is first harvested in the second year and the planting is renovated annually. Using this system, strawberry seasons last for three to four weeks from middle May through June. The traditional system has been replaced with an annual plasticulture system in the southern United States ever since the 1980s. In the annual plasticulture system, strawberry plugs (rooted runner tips) are transplanted in plastic covered beds in late summer or fall. Fruit are harvested in spring in the next year. After the fruiting season, the plants are removed. The annual plasticulture system is favored in the south because it has a longer harvest period and produces strawberries with better quality. In Indiana, trials established to test the annual plasticulture system had limited success because of short fall season and harsh[Read More…]


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