150 articles tagged "Cucurbits".

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…]


In the last issue of the Vegetable Crops Hotline, I wrote an article about common diseases of cantaloupe and watermelon transplants. Based on the samples I have received over the last few days, I would like to write about a disease that is not usually a problem: angular leaf spot. Angular leaf spot affects all cucurbits. In this article, I would like to concentrate on angular leaf spot on cantaloupe and watermelon. Symptoms of angular leaf spot on cantaloupe often consist of brown, necrotic lesions on the margin of true leaves and seed leaves (Figure 1). On watermelon leaves the lesions may appear darker (Figure 2). Under cool, wet conditions, the disease can be quite severe, resulting in hotspots where seedlings are rendered useless for field transplanting. Angular leaf spot may be seed borne. I suspect that the pathogen may also survive on transplant trays and on greenhouse surfaces. Therefore,[Read More…]



Figure 1. A common symptom of gummy stem blight of watermelon is a watersoaked area where the seed leaves attach to the stem.

1. What caused the water-soaked stem of this watermelon transplant? A-damping-off B-gummy stem blight C-Lightening strike Correct Answer: B 2. Is this problem likely to spread to other transplants? Yes 3. Will this problem likely spread in the field? Yes More information about gummy stem blight can be found in the article Cantaloupe and Watermelon Transplant Diseases in this issue.


Fig. 2 Maggot in young onion transplant with a penny referenced for size. Photo by John Obermeyer.

Each and every spring we get reports of poor seed emergence, seedling and transplant damage in early planted crops of all sorts. Most recently in untreated sweet corn, home gardens and transplanted onions. Lucky for us, we got to dive right into this pest and see them in action, but not so lucky for the growers who weren’t expecting it! While we don’t have a lot to offer in terms of a rescue for these crops affected this year, we hope to help you plan for this in the future and understand what the threat looks like for the remainder of the season. There are two different species to blame: the Onion Maggot (Delia antiqua) and the Seed Corn Maggot (Delia platura). There is a third species that attacks brassica crops referred to as the Cabbage Root Fly (Delia radicum). All three are nearly identical to the naked eye but[Read More…]


Figure 3. Anthracnose lesions on watermelon often appear jagged.

Many cantaloupe and watermelon growers are either growing transplants in a greenhouse or are expecting delivery of transplants in the next few weeks. Either way, growers should inspect transplants for disease before planting in the field. Below I will describe several common transplant diseases of cantaloupe and watermelon as well as management options. Gummy stem blight on transplant seedlings may be recognized by the watersoaked area of the stem near the seed leaves (Figure 1). The watersoaked area may eventually turn brown and woody. A closer look at the woody area may reveal the small, dark fungal structures of the gummy stem blight fungus. Medium brown, irregular lesions may also be observed on true leaves. A watersoaked area near the soil line is more likely to be damping-off (Figure 2). More information about damping-off can be found in previous issue’s article Damping-off of Vegetables. The fungus that causes gummy stem[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.



Dear Watermelon Growers, At our past winter technical meeting, several growers suggested fertilizer recommendations need to be reevaluated for watermelon production in our area. This suggestion is timely and critical. We plan to initiate a project for the 2020 watermelon production season to reevaluate the fertility and irrigation practices used in Indiana.  We will identify 7-10 watermelon fields with different irrigation and fertility practices. We will collect soil samples and plant tissue samples at different crop growth stages. Lab results will be shared with growers immediately after they are received. Growers who wish to closely watch the nutritional status of the watermelon plants may want to take this free opportunity. As part of this project, we will collect information about fertilizer and irrigation application, and approximate yield of the evaluating field from growers. Summarized results of this project will be shared at the next Southwest Indiana Vegetable and Melon Growers[Read More…]


Warm-season vegetables like tomato, cucumber, pepper etc. often receive premium prices if they were sold at farmers’ markets earlier in the season. The same happens on summer squash, with the different fruit shape and color, summer squash provides a great diversity to the market. High tunnels that  are planted with warm-season vegetables are often closed to maintain heat inside the structure in the spring. Growers often hesitate to bring beehives to high tunnels because of the increased production cost and potential worker safety concerns. Under such circumstances, crops that can set fruit without pollination (parthenocarpic) have an advantage for early-season high tunnel production. Previous studies indicated parthenocarpic character exists in some summer squash cultivars. But such information is not always clearly indicated in seed catalogs. Without knowing the information, farmers may miss the opportunity of growing summer squash and targeting for an early harvest in high tunnels. In the spring[Read More…]


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