111 articles tagged "Cucurbits".

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…]


Figure 3. The fungus on this senescent female pumpkin flower (Choanephora sp.) is growing on a flower which did not develop properly.

There has been some concern about poor fruit set in pumpkin fields that otherwise have healthy vigorous vines. This summer we have experienced above normal temperatures for much of the pumpkin fruit set season and I suspect that has played a role. This article will consider temperature as well as other factors that influence pumpkin fruit set. In order for fruit set to take place, male and female flowers must be open on the same day, pollinating insects must be active, the plant must not be too stressed and it must have an adequate level of carbohydrates. Growers can influence some of these conditions. High temperatures promote death of female pumpkin flowers while still in the bud stage. Varieties differ in the their sensitivity to high temperatures. To determine whether flowers have died early in development requires close inspection of the pumpkin vine. An aborted bud often dries up and[Read More…]


Figure 3. Plant infected with bacterial wilt, transmitted by spotted and stripped cucumber beetles

In issue 619 of the Vegetable Crops Hotline newsletter I reported that during April 2016 research focusing on the development of a unique market segment for Indiana melon growers was initiated. The research aims to demonstrate that through the use of high tunnels or greenhouses growers will be able to market melons earlier and increase yield while keeping quality undeniably high. Initial research focused on variety evaluation in a soil and soilless production system in high tunnels and a greenhouse, where the plants were trellised vertically. In the long term, we aim to establish the best production practices for high tunnel and greenhouse growers in Indiana and we will do a complete life cycle analysis to determine the profitability of the proposed production systems. Well it sounds all easy to do, but in reality I have experienced several production related issues during the growing season. Let me present to you[Read More…]


Figure 5: Tirreno, an Italian netted variety, orange flesh color

Indiana is a very important player in the domestic melon market. The total acreage planted in Indiana peaked in 1997 at 3,600 acres. In that year the total production was 455,000 cwt with an average income of $16.00 per cwt. The total farm value of production was $7,280,000 ($2,022 per acre). Yield has increased since 1997 from 130 cwt per acre to more than 200 cwt per acre in 2014. The Indiana melon growers have lost a significant share of the melon market since the 2011 and 2012 food borne illness outbreaks. Compared to 2011, the acreage planted and production in 2015 decreased by 900 acres and 52% (300,000 cwt), respectively. Quick Facts about Indiana Cantaloupe Transplant Production: March/April Planting Season: April – June Harvest Season: June – Sept. Plant Population (2.5 ft. x 6 ft.): 2,904 plants per acre Total acres planted: 2,100 acres (2013), 1,900 acres (2014), 1,800[Read More…]


Cucurbit downy mildew has been observed on cucumber and cantaloupe near Wanatah, in La Porte County, Indiana. Downy mildew has also been confirmed on cucumber in St. Joseph County Michigan, just northeast of Elkhart, Indiana as well as on processing pumpkin in central Illinois. Downy mildew of cucurbits has also been reported in southern and central Kentucky and north-central Ohio. All cucurbit growers in Indiana should be scouting and managing for downy mildew. The organism that causes downy mildew of cucurbits doesn’t overwinter in Indiana. It has to be blown in every year. It is common for downy mildew to start the season in the Gulf States and migrate north with the cucurbit crops. Downy mildew apparently overwinters in northern Michigan/southern Ontario in greenhouses where cucumbers are grown year round. Therefore, downy mildew is often found in Michigan before it is found in Indiana. Many cucumber varieties have some resistance to downy mildew. For susceptible[Read More…]


Figure 2. Cross stitch with large lesions.

Cross stitch of watermelons is a physiological disorder (not caused by an infectious disease) first reported in 1990s on watermelon fruit. It received the name because the symptom looks like cross stitch. One or more rows of oval-shaped lesions lie along with the longitudinal axis of the fruit. These lesions are normally more close to the stem end of the fruit (Figure 1). Sizes of the lesions range from a quarter inch to more than 2 inches. When the lesions are small, it normally does not affect interior flesh quality. However, if lesions develop into large gaps, it could lead to fruit rot (Figure 2). Cross-stitch symptom has been noticed in several watermelon production areas, however, causes of the symptom is still largely unknown. In most of the years, this is a minor problem. However, we have received more reports of cross-stitch  on watermelon fruit this year. In one case,[Read More…]


For many vegetable growers, the season is in full swing. All that hard work in season preparation, planting and maintenance is paying off with harvest. One of the on-going season maintenance issues is applying fungicides. In other articles, I have described how and when to spray. In this article, I want to address when to stop. To limit the scope of this article, I will concentrate on tomato, cantaloupe and watermelon crops. These are crops where the fruit is consumed, not the foliage. For most vegetable crops, there is no need to apply a fungicide shortly before the final harvest. Foliage needs to be protected to preserve fruit quality. A plant with reduced foliage will produce a smaller fruit and/or fruit that have fewer sugars and other desirable compounds. I don’t know how much foliage needs to be reduced to affect fruit size or quality. However, I do know that for many foliar diseases, symptoms will not be obvious[Read More…]


Figure 1. Squash bug and its eggs (photo credit John Obermeyer)

Squash bug is the most consistent insect pest of squash and pumpkins and is the most difficult to control. The key to management is early detection and control of the nymphs. The adults are extremely difficult to kill (Figure 1). Foliar insecticides should be applied to control the nymphs (Figure 2) when you have more than an average of one egg mass per plant. When you find egg masses, mark them with flags and check every day or two to see when they hatch. When many of the egg masses are hatching, that is the time to begin application. Since eggs are laid and hatch over an extended period of time, several applications may be required. Brigade®, Mustang Max® and Warrior® have provided excellent control.  


I have received several calls about pumpkins recently. This article will outline a few steps growers should think about to prevent diseases in pumpkins. Virus diseases – There are several virus diseases that affect pumpkins in the Midwest. The most important diseases include: papaya ring spot, watermelon mosaic and zucchini yellow mosaic virus. Aphids transmit all these diseases. Many of the aphids responsible are carried up from the south each year on winds. Therefore, aphids with virus are more common later in the summer; pumpkins planted later in the season are more likely to be affected with one of the virus diseases listed above. Plant pumpkins by about June 15 to avoid having the fruit set during the period of high virus disease pressure. Powdery mildew – It is nearly impossible to find a pumpkin vine in August without powdery mildew. However, this disease does not have to affect production. The first decision a[Read More…]


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