89 articles tagged "Cucurbits".

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 water soaked area of the stem near the seed leaves (Figure 1). (A water soaked area near the soil line is more likely to be damping-off.) The water soaked 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. The fungus that causes gummy stem blight (Didymella bryoniae) may survive in crop debris, thus overwintering in the field[Read More…]


Figure 2: We often observe Fusarium wilt in transplant trays in a clustered distribution. We believe that Fusarium wilt may spread from plant-to-plant within a transplant tray, perhaps by soil splash or spores that have been observed on diseased seedlings.

Fusarium wilt is one of the most serious diseases of watermelon in the Midwest. The disease often causes a one-sided wilt 2-3 weeks after transplanting. Whether a plant is affected, and to what degree, depends on the population of the long-lived spores in the soil that the roots contact. However, Fusarium wilt of watermelon is not known to spread from plant to plant in the field. This is in contrast with a disease such as anthracnose which can spread from plant-to-plant rapidly in one season. Occasionally, Fusarium wilt can be observed affecting commercially produced watermelon transplants in new trays and virgin soilless mix. The most likely explanation for such outbreaks is the introduction of Fusarium wilt on seed. The distribution of Fusarium wilt from seed should appear random. However, we often observe a clustered distribution of affected seedlings as seen in Figure 1. We conducted an investigation to determine whether[Read More…]


As part of a multi-state effort being headed by Dr. Ian Kaplan at Purdue University in the Department of Entomology, we are investigating how to best manage insect pests on cucurbits, in our case watermelons, while having the least possible impact on pollinators. The research is being funded through the USDA/NIFA Specialty Crop Research Initiative. The premise of this research is based on the fact that neonicotinoid insecticides, which are a versatile and powerful pest management tool, have been implicated as a factor contributing to pollinator declines. Thus, farmers growing pollinator-dependent crops—including watermelons—are confronted with a potential trade-off between two competing aspects of crop production: effective pest suppression and successful pollination. Our objective here is to identify insecticidal management strategies that simultaneously optimize pest suppression while minimizing non-target exposure to cucurbit pollinators. To achieve this objective, we are currently looking for producers to collaborate with members of the Entomology Department[Read More…]


Figure 1. Seedless watermelon varieties in 2016 variety trial that have unique rind patterns

— Notes from Watermelon Research and Development Group Annual Meeting and 2016 Indiana Watermelon Variety Trial We are proud to be in Vincennes, the heart of watermelon producing counties in Indiana. In case you are unfamiliar with watermelon production here, Indiana is just behind Florida, Texas, Georgia, California and South Carolina in watermelon production nationwide. Indiana has more than 7,000 acres of watermelons valued at over $30 million value. In the recent Watermelon Research and Development Group (WRDG) annual meeting, the group that comprise members from academia, government and industry discussed watermelon varieties. In this article, I will summarize my notes from this year’s meeting and discuss the varieties we tested in Indiana watermelon variety trials in 2016. Mini-watermelons One of the interesting things I learned in the meeting is from a talk by Mr. Greg Hitt from Walmart. He shared data that shows Walmart increased the sale of mini watermelons[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…]


In issue 619 and 620 of the Vegetable Crops Hotline newsletter I gave you a brief background of the materials used and methods followed during the variety evaluation. I also discussed some of the challenges we encountered while doing the trial work. The varieties evaluated included: Entry # Variety 1 Sephia (Galia type) 2 Tirreno (Italian netted cantaloupe) 3 Rawan (Ananas type) 4 Rowena (Ananas type) 5 Migdal (Galia type) 6 Magnificenza (Italian netted cantaloupe) 7 Kenza (Charentais) 8 Karameza (fully netted cantaloupe) Preliminary data will be discussed in this article. Statistical analysis of all the data has not been concluded and therefore only treatment averages are reported. Yield: One of the criteria that was set for the variety trial was that the fruit size needed to be between 2 – 4 lbs. At Meig’s Farm Magnificenza, Sephia and Kenza produced fruit that varied in weight between 3.28 and 3.96[Read More…]


With the start of pumpkin harvest, it is a good time to review important considerations for harvest and postharvest storage of pumpkins and winter squash (butternut, acorn and hubbard squash etc.). First, pumpkin and winter squash should be harvested fully mature to reach their optimal quality and fulfill their potential for long shelf lives. Characters indicating fruit maturity include loss of rind surface gloss, ground spot yellowing, and hardening of the skin to the level that it is resistant to puncture with a thumbnail. Except for some striped varieties, mature fruit should have solid external color. If fruit have to be harvested pre-mature because of plant decline, these fruit won’t store as well as mature fruit. The best practice is to harvest the fruit as soon as they are fully mature and then store under proper conditions. If mature fruit are left attached to the vines, it increases the chance[Read More…]


Downy mildew has now been observed on butternut squash, jack-o-lantern pumpkins and cucumbers in Knox County. The list of cucurbits observed in Porter County has been updated to include butternut squash and giant pumpkin. All cucurbit growers should assume that downy mildew is present nearby and may attack any cucurbit crop. However, it is not clear what affect downy mildew may have on cucurbit crops this late in the season. Pumpkin growers who expect to harvest in the next few weeks may not need to take any management steps at this time. Downy mildew affects only leaves; stems and fruit are unaffected. Indirect effects of downy mildew in fruit are unlikely to be observed in a few weeks. Another article in this Hotline issue discusses the question of when to stop managing diseases in pumpkins. If the decision is made to apply fungicides, this article https://vegcropshotline.org/article/cucurbit-downy-mildew-watch/ or the Midwest Vegetable Production Guide mwveguide.org will help to select a[Read More…]


Several pumpkin growers have asked me when to stop managing for pumpkin diseases. That is, when should a pumpkin grower stop applying fungicides? I cannot provide a definitive answer for this question; every grower will have to make his or her own decision. Below, however, are some factors to consider. Estimate the crop yield – walk through the field and evaluate the yield of pumpkins that are ready to harvest. Be sure to only consider fruit of marketable quality. If the yield is at or above what is expected, it may be time to put the sprayer away. Estimate when harvest will take place – Pumpkins that are scheduled for harvest in the next week or two are less likely to need any fungicide treatment. A longer period to final harvest may indicate that there is time for immature fruit to ripen. For example, pumpkins that are to be picked by the consumer up to Halloween may[Read More…]


Over the past several weeks, there have been a number of reports of high populations of aphids on cucurbits, as well as report of disappointing levels of control with various insecticides. Without getting into the specifics of individual complaints, here are some suggestions for improved control of aphids. Remember that our primary method of control of aphids is natural enemies. There are a wide variety of predators and parasites than usually keep aphids at reasonable levels. Usually, an outbreak of aphids is an indication that a grower has done something to kill off the natural enemies, which allows aphid populations to reproduce unchecked. And, aphids have a very high reproductive capacity, so without those natural enemies they can build up in number very quickly. Obviously, there are other pests that cucurbit growers need to control, so some disruption of the natural enemies is to be expected. However, growers should only[Read More…]


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