38 articles tagged "Watermelon".

Figure 1. Striped Cucumber Beetle feeding on a watermelon.

Striped cucumber beetle can be a significant pest in watermelon production systems. These pests can cause feeding damage to roots, stems, leaves, and flowers of plants as well as the watermelon fruit itself (Figure 1). In large enough densities, this damage can lead to economic loss. The economic threshold for striped cucumber beetles in watermelon has been set at 5 beetles per plant, since they are not susceptible to bacterial wilt. When densities of the beetles reach this level, growers should treat their fields with an insecticide to avoid yield loss. To make good decisions, pest densities should be determined with scouting. To investigate the pressure of striped cucumber beetles on commercial watermelon fields in Indiana we worked with 16 growers during the summers of 2017-18. Fields ranged in size from less than half an acre to 100 acres. The growers used a variety of management strategies and insect scouting[Read More…]


Insecticides are often needed to control pests in vegetable crops, but in crops that require pollinators we often worry about the impact those insecticides may have on those pollinators (Figure 1). In the summer of 2018, a team of researchers at Purdue University explored the effects of insecticide applications on watermelon yield across Indiana, considering their impacts on both pests and pollinators. Using 5 of the Purdue Agricultural Centers (PACs), pairs of ½ acre watermelons plots were planted, each in the middle of a 15-acre corn field (10 total plots) (Figure 2). The two watermelon plots at each site were assigned either to a conventional or an integrated pest management (IPM) system. The corn surrounding the conventionally managed watermelons had a neonicotinoid seed treatment, the watermelons were given a neonicotinoid soil drench at transplant, and 4-5 pyrethroid sprays were applied throughout the summer regardless of pest pressure. The IPM system[Read More…]


Figure 2. A severe case of hollowheart watermelon.

Hollowheart of watermelons is a physiological fruit disorder. Flesh separates inside of the fruit, typically forming three gaps (Figure 1 and 2). In severe cases, hollowheart could cause watermelon load rejection. Watermelon fruit that has hollowheart tends to be triangular shaped. Poor pollination is the primary reason causing hollowheart. Scientists were able to prove that seedless watermelons are more likely to develop hollowheart when the pollenizer plants (diploid watermelons) are located further away from the seedless plants. The study found hollowheart incidence starts to increase when the distance between the seedless plant and the pollenizer plant is more than 6 feet. Cold weather and the lack of bee movement during pollination period causes poor pollination and increases the chance of hollowheart. Some growers use mixed pollenizer plants with different flowering peaks to ensure availability of pollen matching the blooming period of seedless plants. Bumblebees, in addition to honeybees, are sometimes used; bumblebees are relatively more[Read More…]


Watermelon harvest is in full swing in southern Indiana. At this time, we frequently see many types of leaf symptoms. Some of them are caused by foliar diseases, such as anthracnose, Alternaria leaf blight and gummy stem blight. These diseases require special attention, normally in the form of fungicide sprays, to slow spread of the disease. However, the appearance of a moderate amount of foliar disease in mid-season doesn’t necessarily need an immediate fungicide application. Other leaf symptoms may not be caused by diseases or insects. Here are some examples of leaf symptoms that are not associated with a pathogen. It is important to correctly identify the source of the symptom to prevent unnecessarily pesticide spray. In the article When a yellow leaf is just a yellow leaf, Dr. Dan Egel discussed general rules for determining if the symptom is a disease or not. If you are not certain whether the symptom[Read More…]


The Purdue MELCAST system allows growers to apply foliar fungicides according to weather conditions instead of using a calendar-based system.

MELCAST is a weather-based disease-forecasting program that helps growers schedule foliar fungicides. MELCAST stands for MELon disease forCASTer. This program, designed by Dr. Rick Latin, Professor of Plant Pathology at Purdue University, keeps track of weather conditions so that cantaloupe and watermelon growers can apply foliar fungicides to their crops when they are most needed. The foliar diseases that MELCAST was designed for are Alternaria leaf blight, anthracnose and gummy stem blight. In a typical year, MELCAST will save growers 2 to 3 foliar applications of fungicides without sacrificing yield. MELCAST works by having growers apply fungicides at specific Environmental Favorability Index (EFI) values instead of using a calendar-based schedule. The extension bulletin “Foliar Disease Control using MELCAST” BP-67 describes this program in more detail. To use MELCAST, follow these steps: Apply your first foliar fungicide application when vines first touch within a row or earlier. Find a MELCAST site[Read More…]


This article provides more detailed information about this herbicide. How does Chateau® herbicide work Chateau® is a group 14 mode-of-action herbicide. Compounds in this group are most active on broadleaf weeds. Before Chateau® became available,  no other preemergence herbicide with the same mode of action was labeled for use in watermelons and cantaloupes. The active ingredient of Chateau® herbicide, flumioxazin, controls susceptible weeds by inhibiting propoporphyrinogen oxidase (PPO), an enzyme that controls chlorophyll synthesis. Because of chlorophyll production inhibition, a chain reaction occurs within the plant that causes cell membrane disruption. Chateau® herbicide can assist in the postemergence control of emerged weeds. It is taken up by roots, stems, or leaves of young plants. It kills weeds through direct contact. There is usually little or no translocation of the herbicide within plants. Foliage necrosis can be observed after 4 to 6 hours of sunlight following the herbicide application. Susceptible plants[Read More…]


Chateau SW® herbicide now has a 24(c) special local needs label for cucurbits. This product is produced by Valent, but the label is held by the Indiana Vegetable Growers Association (IVGA).  To obtain a label, one must be a member of the IVGA, pay an annual $100 processing fee, read and understand the ‘conditions for use’ and have the appropriate forms signed and notarized. One cannot use Chateau SW® without completing these forms and obtaining a label. This process must be repeated every year. Chateau® can only be used in row middles between raised plastic mulch beds that are 4 inches higher than the treated row middle. The mulched bed must be at least 24 inches wide. The application must be directed between rows with a shielded sprayer. Chateau® cannot be applied post-transplant. Do not apply more than 4 oz. of Chateau® per acre at a broadcast rate during a single application.[Read More…]


Figure 1. Watermelon variety trial at Southwest Purdue Ag Center.

Seedless watermelon variety trials have been conducted at the Southwest Purdue Agricultural Center in Vincennes, IN for more than 20 years. In 2017, we evaluated the performance of 37 standard size seedless watermelon varieties and 4 mini watermelon varieties. This article introduces the top performing varieties in our trial in 2017. Standard size seedless watermelons Red Amber. This is a new variety. It had the highest yield among 37 varieties in 2017. Rind pattern of the variety is a medium green background with a medium dark crimson stripe. Average fruit weight in our trial was 16 lb. Red Amber had relatively firmer flesh compared with other varieties. 9651 and 9601. Both 9651 and 9601 are sugar baby type watermelons that have solid green rinds. Fruit shape is round to oval. Both varieties had a high yield in 2017, especially 9651. Average fruit size of 9651 was 16 lb and 9601[Read More…]


After harvest, storing vegetables in optimal conditions is important to ensure the whole season’s hard work has paid off. This article discusses the optimum storage conditions for tomato, pepper, cucumber, watermelon, cantaloupe and sweet corn. Tomato Ideal storage conditions for tomatoes depend on the maturity stage of picking. If tomatoes are picked at mature green, store them in 66 to 70°F with 90 to 95% RH would encourage uniform ripening. Temperatures above 81°F reduce intensity of red color and reduce fruit shelf-life. Green tomatoes are chilling sensitive. If the temperature is below 55°F, fruit may develop chilling injury. Red tomatoes are safe to store at 50°F, however, flavor and aroma may be negatively affected compared to storing them at 55°F. Pepper Optimum storage condition for peppers is 45 to 55°F with 90 to 95% RH. Temperatures lower than 45°F may cause chilling injury. Colored peppers are in general less chilling[Read More…]


Figure 1. Grafted Fascination plants were grown on the right bed, ungrafted plants were grown on the left bed. The field were naturally infested with Fusarium wilt.

Watermelon production is threatened by Fusarium wilt, a widely distributed soilborne disease that can cause yield losses up to 100%. Currently, there are no watermelon varieties that are completely resistant to all races of Fusarium wilt. One way to control the disease is through grafting. The grafted plant combines a watermelon cultivar with a squash rootstock that has resistance to Fusarium wilt. In a study conducted at Southwest Purdue Ag Center (SWPAC), we found grafted watermelons significantly reduced disease incidence, and more than doubled watermelon yield in a Fusarium wilt infected field (Figure 1). In addition to controlling Fusarium wilt, grafted watermelons often show substantial advantages in early watermelon production due to cold tolerance from rootstocks. In a study conducted in Arizona, grafted watermelons that were transplanted in the field two months before soil temperatures reached 70 °F had twice as much yield as ungrafted watermelons grown in the same[Read More…]


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