Veggie Extras

The articles posted here represent subjects that may be more in-depth or descriptive than those articles posted regularly in the Vegetable Crops Hotline.

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It got my attention recently that the newest USDA planting map is shifted northward compared to the one before. The planting map is based on the coldest winter temperatures of the past 30 years’ record. The most recent map is generated from data in 1981-2010, the prior one is based on data from 1971-2000. Planting zones were changed from Zone 5 to Zone 6 in several places in middle and northeast Indiana. In the map before, green areas are where planting zones have been changed. Undoubtedly, these changes will make a difference in plants that could survive in these areas in the winter. It may also affect vegetable production in the state, especially winter and protected cultural productions. Want to know which zones you are located? Check this site http://noaa.maps.arcgis.com/apps/MapSeries/index.html?appid=5f617f338eb5431eb3700e8685eccaf7

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One of the most common diseases of pumpkin in Indiana is powdery mildew.  Growers are naturally anxious to observe whether the fungicide they have been applying for this disease has been effective.   Therefore, many pumpkin growers scout their fields for disease. Although powdery mildew is relatively easy to recognize, it is possible to become confused.   Figure one shows two pumpkin leaves.  The bottom leaf has the white, sporulation of the powdery mildew fungus in colonies randomly scattered across the leaf.   The top leaf, has silvery coloration primarily along the vein.  This latter leaf is a healthy variegated leaf.   Some pumpkin varieties show this type of variegation more than others. It may be a good idea to study the photo shown here so that one can tell the difference between a pumpkin leaf with the disease powdery mildew and a healthy leaf that is merely variegated


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Daikon radish is a member of Brassica family. It forms a large white tap root like a giant carrot. The tap root (12 to 20 inches long and 2 to 4 inches in diameter) penetrates into the soil leaving 2 to 6 inches protruding above ground.  Radishes are cool-season crops. They are best grown with air temperatures in the range of 50 to 65°F. They grow fast, forming a dense canopy in the fall.  They are winter killed when temperatures drop to low 20s °F for a few consecutive nights. Daikon radish is a common and popular vegetable consumed in the southeast and Eastern Asia (Figure 1). The large and white roots have a favorable mild flavor, very low calorie content and rich in vitamin C. Fresh or picked diced daikon roots are important ingredients in a variety of dishes and soups in Asia cooking. Leaves are also consumed as[Read More…]


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As Thanksgiving approaches, I have noticed that the gourds I set out before Halloween are starting to rot. But before I throw them away, what is causing the lesions? The circular lesions that can be seen in Figure 1 and 2 are symptoms of anthracnose of gourd.   That is, the pathogen that is causing the lesions in the accompanying figures is Colletotrichum orbiculare.   This is the same pathogen as the one that causes anthracnose on other cucurbits such as watermelon. (It is possible that the anthracnose is caused by a different species of Colletotrichum. Even if the pathogen is C. orbiculare, I am not sure of the race. More research would be required.)     A second question is how the pathogen contacted the gourd sitting in a basket in my house since early October.   This is a harder question to answer.   My guess is that the pathogen contacted[Read More…]


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I probably spend too much time posting photos of diseased vegetables on-line and presenting vegetable disease symptoms in presentations.   My excuse is that recognizing the symptoms of what might be a disease seems important to me.   However, it might be just as important to recognize symptoms that are not of an infectious disease. See below for some photos of leaves that do not have an infectious disease.   The leaf in Figure 1 is a relatively old leaf.   Older leaves tend to turn yellow with age.   One reason for this is that nitrogen is mobile in the plant.  When newer leaves are formed and need nitrogen, it can be pulled from the older leaf.   This means the older leaf looks yellow and perhaps brown around the edges. It is possible that non infectious problems can be important problems.   However, none of the leaves here have symptoms of a problem[Read More…]


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Driving across IN now, it is not uncommon to see many recently built high tunnels standing along the roadsides. These structures have become an important tool for farmers to extend production seasons of vegetable and fruit crops. Compared with traditional greenhouses, high tunnel demand much less energy as they are heated by solar energy and ventilated through natural air circulation. Similar to high tunnels, Chinese-style solar greenhouse is an important tool for season extension in specialty crop production in China. The structures are facing south, featured by supporting north walls (Figure 1 and 2). The north walls are essential in maintaining temperatures inside the structure. They are made up with materials having good insulation properties and with a thickness more than 30 inches. The south sides are arch-shaped, supported by steels and covered with polyethylene or polyvinyl chloride films. From north to south, the structures span 26-46 feet. A short[Read More…]


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Recently I observed lesions of leaf mold of tomato in our high tunnel at the Southwest Purdue Ag Center.  I thought I would share these photos since the lesions can be variable.   More information about this disease can be found at here.


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We recently published an article in the Hotline about gray mold of tomato.  That article and more details about this disease can be found here. In this short note, we want to share examples of the relationship of gray mold and tomato plant injury. In the figure 1 above, a pruning injury of tomato in a commercial greenhouse has become necrotic and a gray mold infection is starting. Figure 2 is from our research high tunnel.  In the photo, one can see where there was an abrasion, probably due to tying the plant in the greenhouse. This injury allowed the gray mold fungus to begin to grow.  Not only will this infection cause a die-back, but the spores produced may cause the disease to spread.  We clipped off this branch to stop the spread of the disease. The photo is taken outside of the greenhouse for better lighting. The lesson here is[Read More…]


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White mold of watermelon – Usually when I write about a vegetable disease it is because the disease may cause important economic loss. Once in a while, however, a disease I find is more a curiosity than a real problem. So, go ahead and read this article about white mold of watermelon. But please don’t worry about this disease. Simply, watch for these symptoms and let me know if you have questions. Readers may have heard me ‘talk’ about white mold of tomatoes. The fungus that causes white mold, Sclerotinia sclerotiorum, has a wide host range. Important hosts include bean, cabbage, potato, lettuce and sunflower in addition to tomato. More about the disease on tomato can be found here. If you have never heard me talk about white mold of watermelon, don’t feel left out. I don’t talk about white mold of watermelon since I have only observed the disease twice in 21[Read More…]


​ Last year at the Southwest Purdue Agricultural Center (SWPAC) we conducted a tomato high tunnel trial described here. In this article, I would like to talk about the trial we will conduct in 2015, a repeat of the 2014 trial. In particular, I would like to talk about what we have done for fertility. Before deciding on a fertility scheme, it is critical to conduct a soil test each year. Our soil test from November 2014 showed that our high tunnels were low in sulfur, boron and moderately low in zinc. In fact, plant tissue tests conducted during the 2014 season were low for both sulfur and boron. As a result of these tissue tests, we added a 10% liquid boron product and ammonium thiosulfate (7%) to the fertigation during the 2014 season. However, the next set of tissue tests carried out during the 2014 season also came back[Read More…]


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