111 articles tagged "Cucurbits".

Figure 1. A cucumber plant grown in a high tunnel died because of bacterial wilt.

Bacterial wilt is one of the most destructive diseases in high tunnel cucumber production. The reason bacterial wilt is so important is because, like other wilt diseases, it ties up with the entire vascular system of a plant, causing systemic effects (Figure 1). The relatively less important roles that other cucumber diseases play also make bacterial wilt the major limitation for high tunnel cucumber production in Indiana. For example, common cucumber diseases such as angular leaf spot, anthracnose and Alternaria leaf blight seldom occur in a high tunnel scenario; improved resistance to powdery mildew was observed in some of the newly developed cucumber varieties; downy mildew in general does not occur in Indiana until end of the high tunnel cucumber production season. The causal organism for bacterial wilt of cucumbers is Erwinia tracheiphila. After the bacteria enter the plant vascular system, it multiplies quickly. As a result, it interferes with[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…]


Entomologists are looking for growers willing to participate in research examining the detection and distribution of striped cucumber beetles. We would like to visit your fields on multiple occasions this year to count the number of cucumber beetles we encounter in your crop. If you grow slicing cucumbers in the field, and are interested in helping to improve our sampling recommendations for this pest, please contact Dr. Laura Ingwell at (765) 494-6167 or lingwell@purdue.edu


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 3. A cucumber beetle on the 0.7 x 1.0 mm screen (photo credit: John Obermeyer)

One of the most problematic insect pests that organic vegetable growers have to deal with is the striped cucumber beetle. The insect feeds on all the cucurbit crops, but can be particularly devastating to muskmelons and cucumbers because those two crops are susceptible to bacterial wilt of cucurbits, which is caused by a bacterium carried by the beetles. The only way to avoid this devastating disease is to prevent the beetles from feeding on the plants. There are no effective organic insecticides for managing striped cucumber so we have to look for alternative methods. Row Covers: Row covers can be used to physically prevent beetles from feeding on the plants. To be effective, these need to be placed over the plants immediately after transplanting or before direct seeded crops emerge. The edges of the row covers should be sealed with soil to prevent the beetles from crawling under the fabric[Read More…]


Entomologists are looking for growers willing to participate in research examining the detection and distribution of striped cucumber beetles. We would like to visit your fields on multiple occasions this year to count the number of cucumber beetles we encounter in your crop. If you grow slicing cucumbers in the field, and are interested in helping to improve our sampling recommendations for this pest, please contact Dr. Laura Ingwell at (765) 494-6167 or lingwell@purdue.edu


It’s that time of year, where we are prepping high tunnels and getting back into the full swing of production, slowly, here in the Midwest. Many of you have already begun to transplant and may have encountered your first pests on these new crops. Aphids are one that remain a problem in high tunnels, and may even have plagued your winter production (Figure 1,2,3). Some keys to preventing or controlling these pests rely first on sanitation and then careful scouting. Try to remove any green bridge material that may already be infested before transplanting into the space. This includes weeds, lingering winter crops or residues. Having a week without vegetative hosts should get rid of any overwintering residents. After transplanting scout diligently, at least weekly, or more often on susceptible young transplants. Aphid infestations tend to begin on the growing points or younger tissues of the plant. Be sure to[Read More…]


Figure 2. Plants died in the second day after average soil temperature was 54 °F

Growers start to plant tomatoes in unheated high tunnels around the end of March in southern Indiana. Around that time, there may still be a few light frosts, or even heavier ones, like the one we just experienced in the past week. With additional help from row covers inside of high tunnels, temperatures normally can be maintained above 32°F. Tomatoes typically do not have problems with the short-term low temperatures. However, this may not be the case for cucumbers. Although they are both warm season crops, Cucurbits (cucumbers, cantaloupes, and watermelons) are much more cold sensitive than Solanaceous crops (tomato, pepper). From a temperature perspective, this article discusses important considerations for deciding the time for planting cucumbers in a high tunnel. The best condition to grow cucumbers is when soil temperatures are above 70°F. This situation may not happen until the middle of May inside of the high tunnels, according to our[Read More…]


Figure 1. Powdery mildew causes talc-like lesions on pumpkin leaves.

Powdery mildew is a foliar disease of all plants in the cucurbit family.  The talc-like symptoms on leaves are relatively easy to identify  (Figure 1).  More about powdery mildew of cucurbits can be found at this link https://vegcropshotline.org/article/powdery-mildew-of-cucurbits-2/.  The remainder of this article is an update. There are several systemic fungicides which are recommended for powdery mildew of cucurbits. These include:  Aprovia Top®, Fontelis®, Luna Experience®, Merivon®, Procure®, Quintec®, Rally® and Torino®.  Recently, fungicide resistance to the product Torino® was discovered in eastern New York. I don’t know if the strains of the powdery mildew fungus we have in Indiana are resistant to Torino® or not.  Growers should scout their fields for the effectiveness of Torino® and other products. It is always best to alternate systemic fungicides for the management of powdery mildew of cucurbits. If possible, alternate between 3 or 4 products that have different modes of action. Not only[Read More…]


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