103 articles tagged "Cucurbits".

Anthracnose on watermelon fruit, caused by Colletotrichum orbiculare, is typically round and sunken. (Photo by Dan Egel)

​Late in the 2015 season, I observed some unusual symptoms of anthracnose on watermelon fruit. I wanted to discuss these symptoms, but first a little background of cucurbits. An extension bulletin on this subject may be found at https://www.extension.purdue.edu/extmedia/bp/bp-180-w.pdf. Anthracnose of cucurbits, caused by Colletotrichum orbiculare, is responsible for lesions on leaves, stems and fruit. Crops affected include cucumbers and cantaloupe, however, watermelon is the host most often affected in Indiana. Although lesions on leaves and stems can cause significant loss, it is the lesions on fruit that cause direct yield losses. Lesions on watermelon fruit tend to be close to the ground where the fruit tends to stay wet. These lesions are typically round, sunken and orange to salmon colored (Figure 1). However, the lesions I observed toward the end of the 2015 season differed from the typical. Instead of regular round lesions, the symptoms I observed on the bottom of affected watermelon were[Read More…]


Solid green stems on fully mature pumpkins make a quality jack-o-lantern. (Photo by Liz Maynard)

​Pumpkin season is here. Keeping up with best management practices through harvest and storage will help the year wrap up on a good note. The steps below are a reminder of actions that can make a difference. Handle fruit as little as possible. Harvest fully orange and healthy pumpkins. Half-orange pumpkins may turn orange but quality and storage life will be reduced. Use a sharp knife or loppers to cut pumpkins from the vine. Leave stems long enough for an attractive product. Carry the pumpkin like a ball, not by the stem, or ‘handle.’ Brush off soil that sticks to the pumpkin. If pumpkins are washed, include a labeled sanitizer in the wash water and dry pumpkins before storage. Place pumpkins carefully in crates, bins, or trucks, so that the stem of one pumpkin doesn’t damage the rind of another. Watch for and avoid (or pad) sharp edges that could[Read More…]


Photo by Dan Egel

I have observed this disease in several pumpkin fields this year. It is not clear to me why this disease seems to be more widespread compared to recent seasons. However, it makes sense to review Plectosporium blight here. Plectosporium blight is usually not a serious disease. The occurrence of this disease is usually sporadic. However, when it occurs, it can cause yield loss if left uncontrolled. Older literature may list this disease as Microdochium blight. Plectosporium blight can be recognized from the light tan lesions on stems and leaf petioles. Lesions may also occur on the fruit, although these symptoms are less common. Yield loss is most often caused by lesions on the stem adjacent to the fruit—the pumpkin handle. Yellow squash and zucchini squash are also affected. Lesions are often individually spindle shaped. When these lesions occur in large numbers they can give a light gray or white appearance to[Read More…]


​When used as a verb, to rogue means to get rid of items that don’t conform to a certain standard. In plant pathology, the word rogue is used to describe a technique whereby diseased plants are removed or rogued to slow the spread of disease. I’d like to describe the practice as it might be used to manage Phytophthora blight of pumpkins. The practice works like this: Under conducive conditions, Phytophthora blight spreads quickly from leaf to leaf and from plant to plant. From a single diseased pumpkin plant, an entire field can become infected. But what if one could rogue the few symptomatic plants at an early stage in the disease epidemic? Would this slow the spread of Phytophthora blight? In theory, yes. If one were able to rogue all of the diseased plants in a field, the disease could be slowed. It would be similar to sending sick children home from a classroom; the disease should[Read More…]


​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/.


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