In the past week, we have observed a few cases where newly planted watermelon seedlings were severely damaged or dead (Figure 1). In some fields, we observed rotted roots and lower stems caused by fungal pathogens. However, such diseases were in response to the cold soils and would not normally cause problems in warm soils. Most of the dead plants had intact stems, although growers did report seedcorn maggot and wireworm in the stems of a few dead plants. The same thing happened in May 2016. Coincidentally, rain, cloudy days, and lower than normal temperatures were observed in the same period in both years. Since early May, We have had consecutive days with the lowest temperatures in the 40s°F. There was no risk of frost damage, however, this temperature was low enough to cause chilling injury on young cucurbit plants. This article ‘Protect Early Planted Warm-Season Vegetables from Low Temperature’[Read More…]
Dan Egel
Producing healthy transplants is a critical step for a successful growing season. Choosing the proper growing media is an important first step. Supported by a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, researchers from Purdue have been evaluating different organic growing media with and without adding supplemental organic fertilizers for tomato and cucurbit transplant production. In this article, we have highlighted a few transplant symptoms that are associated with growing media with excessively high or low electrical conductivity (EC) or pH. It is always a good idea to test EC, pH, and other important nutrient content of a medium when you are making your own or using an unfamiliar media. Most soil laboratories provide a saturated media extract test that provides information on these important parameters. More information about this test and suggested range of EC and pH can be found in this article http://www.soiltest.uconn.edu/factsheets/InterpSMEGreenMedia.pdf[Read More…]
Although Indiana is not known for lettuce production, an increasing number of growers find that augmenting retail sales with leaf lettuce can be profitable. Since lettuce is a cool season crop, field planted leaf lettuce around Indiana may be reaching harvest stage. Leaf lettuce can generally be grown with few pests. However, lettuce drop was recently observed in a field of mixed lettuce varieties. Lettuce affected with lettuce drop often first appears stunted. A closer inspection may reveal that outer leaves are wilted and necrotic (Figure 1). Eventually, the entire plant may die. If the plant is removed from the ground and observed, the leaf ribs that touch the ground may exhibit dark, rotten appearing lesions (Figure 2). The lesions may be associated with dark fungal bodies known as sclerotia (Figure 3). Fortunately, lettuce drop does not often spread from plant to plant. The plants that are diseased will most[Read More…]
The Midwest Vegetable Production Guide for Commercial Growers 2018 is available for sale as a hardcopy ($15) or free on-line (be sure to check the article in this issue about changes that have been made to the on-line version). Actually, the Vegetable Guide has been available since last December. The guide may be purchased through the Education Store, at various extension meetings held around the state or from your Purdue University county educator. The website to either view or purchase the Guide, known in Indiana as the ID-56, is mwveguide.org. The Midwest Vegetable Production Guide is a collaboration of 8 states and 9 institutions. Are you thinking that you already have a Vegetable Guide from a past year and wondering if it is worth getting a new one? The article below represents just some of the changes to this year’s Vegetable Guide. New and Revised Sections The three new tables created last year — Selected Information About[Read More…]
A recent observation of gummy stem blight on a watermelon transplant has reminded me to remind growers to inspect seedlings. Whether one is growing transplants or receiving transplants for delivery, seedlings should be inspected for possible disease problems. If one is uncertain of the cause of the symptoms, an official diagnosis can be obtained by sending the sample to the Plant and Pest Diagnostic Clinic. Below I will describe several common transplant diseases of cantaloupe and watermelon as well as management options. I have had similar articles in the Hotline in the past, however, I will use new photos here. Gummy stem blight on transplant seedlings may be recognized by the water-soaked area of the stem near the seed leaves. In this article, I will show a leaf with a lesion of gummy stem blight (Figure 1). A closer look (one may need a 10X hand-lens) at any gummy stem[Read More…]
This disease was recently observed in a tomato greenhouse. This article will review tomato spotted wilt virus symptoms, biology and management. Tomato spotted wilt virus (TSWV) and the closely related Impatiens necrotic spot virus (INSV) are usually observed in greenhouse or high tunnel situations. Both TSWV and INSV affect many hosts, including vegetables and flowering ornamentals. Symptoms vary according to host, stage of plant affected and environmental conditions. Both diseases can cause stunting, yellowing, necrotic rings, leaf mottle and more. Figure 1 shows a tomato leaf with a necrotic mottle caused by TSWV. Figure 2 shows tomato plants stunted as a result of infection by TSWV. Additional symptoms may be viewed here . Since the symptoms of these two viruses vary, plants with suspicious symptoms should be submitted to the Purdue Plant and Pest Diagnostic Laboratory for confirmation of virus symptoms. TSWV and INSV cannot spread without thrips. Thrips are small[Read More…]
Bacterial wilt is a serious pest of cucumbers and melons. This disease is caused by the bacterium, Erwinia tracheiphila. However, it is spread by the striped or spotted cucumber beetle. Most management schemes have concentrated on controlling the cucumber beetle in order to lessen the severity of bacterial wilt. Currently, management of bacterial wilt often takes the form of a soil applied systemic insecticide such as Admire Pro® at transplanting and follow up pyrethroid products applied foliarly about 3 weeks post transplanting. The pyrethroid applications are made when the 1 beetle per plant threshold is met. Every year, there is a melon variety trial at the Southwest Purdue Agriculture Center in Vincennes, IN. In 2018, the trial included several specialty melon varieties. We noticed more bacterial wilt than usual (Figure 1). Therefore, we decided to rate the varieties to see if there were any differences in susceptibility. Figure 2 shows[Read More…]