67 articles tagged "Crop Culture".

Figure 1. Place shadecloth on high tunnels for colored bell pepper production. Photo credit: Ajay Nair

On hot days in the summer, high tunnel growers may wonder whether to place shadecloth on high tunnels. Considering excessive heat inside the structures that may lead to plant stress, blossom drop and unmarketable fruit, there is a rational for doing it. However, it is important to realize the limitations of placing shadecloth on high tunnels in the Midwest. A few years ago, we compared the effect of 30% black shadecloth on temperature and light levels inside a high tunnel. We found shadecloth significantly decreased maximal temperatures for about 10 degrees Fahrenheit while it had no effect on nighttime temperatures.  In terms of light reduction, it ranged from 60% in a sunny day to 30% in a cloudy day. More information about this comparison can be found in the article Temperature and Light Intensity in a High Tunnel Covered with 30% Black Shadecloth in Issue 619. In our experience of[Read More…]

Figure 1. Strawberries are growing in a high tunnel.

Strawberries have a rich flavor; sugar, acid, phenolic content, and aroma all together make the wonderful fruit. Many factors are assumed to affect strawberry flavor. Some are supported by scientific evidence, some may be simply people’s impressions. In this article, we discuss some of the factors that are more likely to affect strawberry flavor. Locally grown strawberries often taste better than strawberries purchased from grocery stores. Part of the reason is that strawberries shipped long distances are harvested a few days before they are fully ripe. The fruit has longer shelf-life but the flavor is sacrificed. We are testing ten strawberry varieties in a high tunnel and in an open-field in southern Indiana this spring. Regardless of cultivars, we consistently noticed better fruit quality (higher sugar content, softer, and much cleaner) for strawberries grown inside of the high tunnel than grown in the open-field (Figure 1). I do not think[Read More…]

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We received calls recently reporting observations of leaf curling on tomatoes. This article discusses factors that may cause tomato leaf curling. In a similar way as other vegetables, hot and dry conditions may cause leaf curling on tomatoes. In late spring and early summer, plants that are actively growing and developing fruit have a high demand for water. Under hot and dry conditions, plants respond by rolling the leaves to reduce the surface area exposed to high radiation. Lower leaves on a tomato plant are often affected first, they may recover if environmental stresses are reduced. Leaf curling itself due to the environmental stresses is not a significant concern, but if the stress condition continues, it may eventually lead to blossom end rot fruit and decreased yield. There is a great variation among tomato varieties in terms of whether the observation of leaf curling suggests the plant is suffering water[Read More…]

Watermelon is best grown at temperatures around 80-90°F. Temperatures above 90°F reduce the growth rate; above 105°F may cause plant injury. Temperatures below 42°F result in watermelon chilling injury; below 32°F will kill watermelon plants. Extended cool days that lead to soil temperatures dropping into lower 50°F can also kill watermelon seedlings. Using low tunnels is one strategy to avoid chilling injury and encourage early plant growth. How does the plastic covered low tunnels modify temperatures in early watermelon season? Figure 1 shows the air temperature comparison between low tunnel (1 mil plastic film, perforated) and without low tunnels. The data was taken from April 24 to May 25, 2020 in a watermelon field at Southwest Purdue Agricultural Center. During the time period, the recorded minimal temperatures were below 40°F for 5 nights. Low tunnels increased the minimal temperature from 0-4.5 degrees (Table 1). Table 1. Minimal air temperatures with and[Read More…]

This article discusses the abiotic factors that may cause deformed strawberry fruit. unevenly developed strawberry fruit (Figure 1): Frost damage is probably the most common abiotic factor causing misshapen strawberry fruit. Temperatures lower than 30°F kill the pistil (female part) of strawberry flowers. Depending on the extent of the injury and the stage of fruit development. The entire pistillate portion of the flower may be killed, which will result in the loss of fruit; Or a few pistils may be killed, fruit expansion stops at where pistils were killed. The damaged fruit then develops unevenly, resulting in misshapen fruit. Lack of wind for pollination is less likely a problem for field strawberry production but can be a concern for high tunnel production. Because high tunnels are typically closed at the peak strawberry blooming stage in order to attract heat. Air movement is very limited inside of the high tunnel that results in poor[Read More…]

This is a newly released video about when to plant watermelons. https://youtu.be/tHT2mAnNRWk Watermelon, cantaloupe, cucumber plants are very sensitive to low temperatures. Even when frost has passed, soil temperatures below 60°F can result in transplant establishment failure. Check soil temperatures before planting. The rule of thumb is to plant watermelon, cantaloupe and cucumber transplants when soil temperatures at the root zone are stable above 60°F. Ideally, watermelon, cantaloupe, and cucumber grow well when soil temperatures are above 70°F.

At Southwest Purdue Agriculture Center in Vincennes, IN. We are conducting trials to evaluate annual plasticulture strawberry production systems. Here are the updates of strawberries from different production systems. In a high tunnel, harvest of fall-planted strawberries started in early April. Cultivars Sensation, Radiance, Ruby June were early cultivars; followed by Beauty, Fronteras. So far, Radiance led the yield. Chandler, San Andreas, Camarosa, Liz and Camino Real were relatively later cultivars. In the open field, most cultivars of fall-planted strawberries were in full bloom. As mentioned in the article Strawberry Cold Protection Made a Difference, they are susceptible to frost damage. Cold protection is critical for them at this stage. Row cover was successfully used to protect the flowers from frost damage last week. Day-neutral strawberry cultivars planted on March 9, 2020 established well. Plants were slightly larger under low tunnels. Frost happened last week killed most of the initiated[Read More…]

Two types of injury on young warm-season vegetable plants are caused by low temperatures: frost/freezing injury and chilling injury. Frost/freezing injury occurs when temperatures drop below 32°F. Ice formation in plant tissue cuts cell membranes. When the tissue thaws, the damage results in fluids leaking from the cell, causing water soaked damage. Frost/freezing injury is detrimental to warm-season vegetables, such as melons, cucumbers, tomatoes, peppers, and beans. To avoid damage, the best way is to plant warm-season vegetables later in the spring, after the last frost has passed. However, weather is difficult to predict, and there is a growing trend of planting early to achieve early harvests. For the early planted warm-season vegetables, here are a few suggestions that may protect plants from low temperature damages. Covering. The idea of covering the seedlings is to create a microclimate around plants. Because the heat accumulated in soil irradiate back at night,[Read More…]

Figure 2. Cold damage on 'Popcorn' stage strawberry flowers.

Spring weather is unpredictable. One of the major risks associated with strawberry production is cold damage in the spring. Open strawberry flowers can not tolerate temperatures lower than 30°F, popcorn stage flowers and tight buds may tolerant temperatures low to 26 and 22°F, respectively. If strawberries are in the early blooming stage, the damage might be delayed harvest. However, if strawberries are in full blooming stage, low temperatures may cause dramatic yield loss. This is because inflorescences are initiated at day length <14h (June-bearing cultivars). If all the flowers were killed by low temperatures before setting fruit, there would be no more flowers for the year. In this article, we update the cold damage that happened last week on plasticulture strawberries in Vincennes, IN. Figure 1 is the recorded temperatures (°F) at the height of strawberry canopies from 2:00 pm Apr. 13— 1:00 pm Apr. 18. Temperatures dropped below 30°F[Read More…]

Figure 1. The two flowers on the left are in 'Popcorn' stage.

Warm temperatures this week greatly encouraged strawberry growth and development. Some of the early cultivars may have entered the open blossom stage especially if they are grown with the annual plasticulture system in southern Indiana. Open flowers cannot tolerate temperatures lower than 30°F, while popcorn stage flowers (Figure 1) and tight buds may tolerant temperatures low to 26 and 22°F, respectively, according to information from Barclay Poling from NCSU. Lower than threshold temperatures may completely kill flowers or damage flowers that lead to misshaped fruit. Depending on the crop stages, this may result in devastating yield losses and/or delay the start of harvest season. According to USDA Midwest Climate Hub briefing, warm temperatures this week will be followed by several days of freezing chances this weekend into early next week, and cold is likely through mid-April at least. The current forecast in southern Indiana predicts low temperatures that are in[Read More…]

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