89 articles tagged "Cucurbits".

​Downy mildew has been confirmed on jack-o-lantern pumpkins in Daviess and Jasper Counties and on acorn squash in LaPorte County. These are the first confirmed reports of this disease on Cucurbita pepo in Indiana in the 2015 season. There are unconfirmed (but reliable) reports of downy mildew on pumpkins in Parke,  Washington, and White Counties. This disease has also been observed on butternut squash (Cucurbita moschata) in Knox and LaPorte Counties and on giant pumpkins (Curbita maxima) in LaPorte County. Read more about this disease at ag.purdue.edu/arp/swpap/VeggieDiseasesBlog/Lists/Posts/Post.aspx?ID=48.


On July 22, I announced that downy mildew had been observed on watermelon in Knox County in southwestern Indiana. This article in the Vegetable Crop Hotline issue 603, https://ag.purdue.edu/hla/Extension/VegCropsHotline/Pages/Latest-Articles.aspx?article=118, describes the outbreak and management options. Downy mildew has now been reported on cucumber and cantaloupe in Knox and cucumber in La Porte County Indiana and pumpkin in Jasper County. Downy mildew has been observed on pumpkins in Mason County in central Illinois. In addition, several counties in Kentucky and Michigan have reported downy mildew, primarily on cucumbers. You may follow the development of downy mildew of cucurbits on this website http://cdm.ipmpipe.org/.


​​Code Red Webinar. Thursday, August 27, 2015. 12:00 P.M. – 1:00 P.M. EDT. The Code Red tool developed by the Purdue Women in Agriculture Team is a must have for every family, business, and farm operation. The tool includes important information such as passwords, bank account information, rental agreements, insurance papers, power of attorney documents, and much more, in one easy location. After completing the Code Red plan, it will become the “go to” tool if something happens to a key member of the management team. We hope this tool will help farm families turn a code red situation into a code green so the business can continue to operate on a daily basis. To participate, register at https://goo.gl/f3gLFM. You will then receive a confirmation email with the link to participate in the webinar August 27. You will also receive a reminder 24 hours before the webinar begins. Illinois Pumpkin Day.[Read More…]


(Photo by Dan Egel)

​We have received a number of reports of outbreaks of spider mites, primarily in watermelons and in high tunnels. The problems in high tunnels are not unexpected because one of the primary causes of mortality in mite populations is rainfall washing them off the plants and, of course, that is lacking completely in high tunnels. With all the rain we have had, it’s a little surprising that we are seeing problems in watermelons, but the older I get, the less I’m surprised by how infrequently arthropods behave the way we expect them to. In both scenarios, we don’t really have treatment thresholds for mites. Generally speaking, if populations are increasing, they need to be controlled. Once the decision to treat has been made, that’s where things get very different. In watermelons, we have a variety of pesticide choices. See page 115 of the Midwest Vegetable Production Guide (ID56) for the[Read More…]


(Photo by John Obermeyer.)

​I have seen more green stink bugs this year than at any time in my career. I have no logical explanation for their abundance. It was thought that as the invasive brown marmorated stink bug became established, it might outcompete the native stink bugs such as the green stink bug, causing numbers to decrease. However, this year, brown marmorated stink bugs have been relatively uncommon, and green stink bugs seem to be everywhere. Stink bugs feed with their sucking mouthparts and are likely to feed on a wide variety of vegetable crops, including cabbage, sweet corn, cucumber, bean of all types, okra, mustard, peas, peppers, and tomato. Check the Midwest Vegetable Production Guide (ID-56) for your particular crop for insecticide recommendations.


Downy mildew causes bright chlorotic lesions on pumpkin leaves that are limited by veins. Lesions eventually become necrotic. (Photo by Dan Egel).

​On July 22, I announced that downy mildew had been observed on watermelon in Knox County in southwestern Indiana. This article https://ag.purdue.edu/arp/swpap/VeggieDiseasesBlog/Lists/Posts/Post.aspx?ID=48 describes the outbreak and management options. Below, I will discuss the whereabouts of additional downy mildew outbreaks on cucurbits.  Downy mildew has now been reported on cucumber in Knox and La Porte County Indiana. Downy mildew has been observed on pumpkins in Mason County in central Illinois. In addition, several counties in Kentucky and Michigan have reported downy mildew, primarily on cucumbers. A photo of downy mildew on pumpkin is shown here for reference (Figure 1). You may follow the development of downy mildew of cucurbits on this website http://cdm.ipmpipe.org/.


​Pumpkins are off to good start and vines are starting to run, which means it is time to think about making a sidedress application of nitrogen. Typically, I recommend to split nitrogen applications half preplant and half sidedress. This is especially beneficial given all of our rain this season. If you relied on preplant N alone, with all of the rain, you may very well have lost almost all of your nitrogen with plants just now starting to set fruit. In my personal scenario, on light colored forest soils (common in So. IL and IN, 1.5-2.5 % organic matter) and given no-till with cereal grain residue I generally shoot for around 100-110 lbs. actual N per year (this would be decreased with more fertile, high organic matter soils) with about 50 lbs. of that at sidedress. In a tilled field, you could decrease this recommendation to around 80 lbs. actual N/A per year. This difference can[Read More…]


Vegetables such as this watermelon may become sunburned if lack of foliage cover exposes the fruit to excess sun and heat. (Photo by Dan Egel)

​Loss of foliage due to poor growing conditions or disease can cause fruit to be exposed to the sun. Hot temperatures and direct sunlight can lead to areas of the fruit that appear bleached or sunburned. Sunburned fruit may not be marketable. To reduce the probability sunburned fruit, every effort should be made to maintain foliage throughout the season. Early wet weather encouraged foliar disease and recent hot, dry weather may have restricted foliar development. Orienting vegetable plantings to minimize damage from the prevailing winds and providing windbreaks such as strips of rye or wheat may help to reduce sunburn. Several products are available that are labeled for use as a preventive for sunburn. These products may be broken into two groups: kaolin (clay) based products and calcium carbonated based products. Kaolin based products include Surround®. Some Surround® products are labeled for use as sunburn protection, while others are not. For example,[Read More…]


Downy mildew of watermelon causes dark brown or black lesions often surrounded by a yellow halo.

This disease has been observed on watermelon in Knox County. The following article will discuss the symptoms, biology and management of downy mildew of cucurbits. Symptoms. The symptoms of downy mildew vary depending on the host.    On watermelon, the lesions start out as chlorotic (yellow) areas that become round and necrotic (brown/black) areas surrounded by a chlorotic halo. Lesions may be limited by veins (Figure 1). Note that leaf lesions of gummy stem blight may have dark fungal structures (pycnidia) present that are lacking with downy mildew. Also, whereas gummy stem blight will affect stems and petioles, downy mildew will not.  Pumpkin lesions also start out chlorotic and are often angular. Eventually, the chlorotic lesions become necrotic. Lesions may be more common along a vein. Lesions on muskmelon often have poorly defined margins and are not as angular as described above for pumpkin.   Cucumber lesions start out chlorotic and very[Read More…]


Magnesium deficiency in cantaloupe often occurs in high

​I have observed many fields of cantaloupes with magnesium deficiency or manganese toxicity. Watermelon plants may exhibit similar symptoms, but not as frequently as cantaloupe. Both disorders are related to acid (low pH) soils and usually occur in clusters in a field. Magnesium deficiency usually appears on sandy ridges and can be recognized by interveinal yellowing and death of tissues on older leaves (Figure 1). Manganese toxicity also first occurs on older leaves but appears in heavier or darker sands, often in low areas of the field. The diagnostic feature of manganese toxicity are the tiny pin-hole type lesions with yellow halos clustered between the veins (Figure 2). Leaves are best viewed when held up to the sun. These disorders can easily be confused with an infectious disease. In particular, magnesium deficiency has been confused with Alternaria leaf blight. Symptoms may seem to “spread” from areas of the lowest pH[Read More…]


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