67 articles tagged "Tomato".

Pith necrosis of tomato may result in dark

​This disease has been reported in two different greenhouse situations. Although the disease is not usually economically important, a brief review of the disease is offered here to help tomato growers differentiate pith necrosis from more important problems. Tomato pith necrosis causes dark brown streaks on tomato stems and leaf petioles (Figure 1).  Often stems may appear twisted and distorted. When cut open, the stem may appear discolored and chambered (Figure 2). Eventually, the affected plant may become stunted and wilt. Tomato pith necrosis is usually found in greenhouses or high tunnels. Because the plant has a discoloration in the stem, it is sometimes confused with bacterial canker, a much more serious disease. A comparison of the two diseases can be found at https://ag.purdue.edu/arp/swpap/Documents/pith-necrosis%20.pdf.  It is not clear how pith necrosis spreads or enters the tomato plant, but it is probably best to remove affected plants and avoid using pruning equipment on diseased plants. When removing[Read More…]

After a brief lull in pheromone trap catches, we have resumed catching earworm moths all around the state. Although most of the counts are relatively low (less than 10 per night), remember that for early planted sweet corn that silks before the neighboring field corn silks, the threshold for treatment is 1 moth per night. So, if you have sweet corn that is in the vulnerable stage, green silks present, treatment is justified if you are catching any earworm moths in your trap.

​Blossom end rot of tomato has been showing up in some protected growing structures. This article reviews the disorder and summarizes preventive practices. Blossom end rot is a physiological disorder caused by a deficient supply of calcium to the developing fruit. It is a common problem on tomatoes, but can also occur on peppers, eggplants, and melons. Blossom end rot appears first as a small darkened or water soaked area, usually at the blossom end of the fruit. This spot darkens, enlarges and dries out as fruit matures. The area may be invaded by secondary decay causing organisms. Prevention is the best way to avoid losses from blossom end rot. Prevention strategies emphasize ensuring adequate supply and availability of calcium, and managing plant growth environmental conditions to promote movement of calcium to the developing fruit. If I could offer just one suggestion it would be to maintain a consistent water[Read More…]

​2015 marks the 40th year of my career as an entomologist and I still am surprised on a regular basis by how insects behave. I put out a corn earworm pheromone trap on May 14 and immediately caught 7 moths that night. Over the next three nights, I caught 36 moths. Typically, the few earworms that we would expect to overwinter here in west central Indiana would emerge about June 20. It has not been an unusually warm spring, to say the least, so it is unlikely that those moths emerged locally. The other possibility is migration from southern areas. Earworm moths often migrate in on storm fronts from the south. However, when moths are blown hundreds of miles on storm fronts, their wings usually get a little tattered. The moths I’ve been catching look pristine, as if they just emerged. So, the bottom line is that I have no[Read More…]

The tomato plants shown here are stunted

​Symptoms of this disease include tomato plants with lower leaves that become yellow (chlorotic) and die; plants that begin to wilt; a lesion on the lower stem at ground level (Figures 1 and 2). If tomato plants are removed from the soil and carefully split open from the ground level, a discoloration of the vascular tissue can be observed (Figure 3). It is important to note that this discoloration does not extend up the stem more than 6 to 8 inches. If the discoloration extends up into the plant canopy, the disease may be Fusarium wilt of tomato. Although growers may observe multiple plants begin to die of this disease over a period of days or even weeks, the fungus does not splash from plant to plant.  Therefore, there should be no plant-to-plant spread in the high tunnel. Temperatures from 68 to 72°F favor Fusarium crown rot and may explain why I observed this disease last week when[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…]

The tomato seedlings above exhibit downward curled leaves (red arrows) which maybe a symptom of ethylene damage and yellow seed leaves with lesions (red circles)

​This is the time of year when growers often call to complain about tomato transplants that do not look right.  One possibility is that the seedlings suffer from heater problems.  In particular, tomato plants are very susceptible to damage from the gas ethylene.  In Figure 1, some of the seedlings have leaves that are curled down and stems that are twisted (epinasty in botanical terms). Epinasty is a common symptom of ethylene damage. Ethylene is a common by-product of incomplete combustion of several different types of fuel.  Incomplete combustion is often the result of heaters that are not working efficiently. Tomatoes are very sensitive to ethylene damage. A second clue is to take a closer look at the yellow seed leaves (Figure 1). Ethylene damage does not include yellowing. Furthermore, there is a spotting on the lower leaves that is not typical ethylene damage. I believe that the symptoms on seed leaves were as a result of a different compound,[Read More…]

Photo by E. Maynard

​Sometimes newly transplanted crops don’t take off like we’d expect. Consider the newly transplanted tomato seedlings in these images. In Figure 1, lower leaves are chlorotic (yellow) and leaflet edges and leaves curl downward. In Figure 2, lower leaves are chlorotic or bleached and some had necrotic (dead) spots. In Figure 3, some leaves have died and others have ‘scorched’ margins or tips. Figures 1 and 2 are from a high tunnel; Figure 3 is from the field. What they have in common is that the tomato plants are not thriving after transplanting. It may be hard to say exactly what is going on with each of these, but it would not be surprising if they were cases of over application of a fertilizer or soil amendment, leading to toxicities for the plant. Ammonium toxicity is common when soil is cool and wet, soil pH is low, and there is[Read More…]

Bacterial spot of tomato is one of the most serious diseases facing tomato growers in Indiana. As described at Vegetable Diseases in Greenhouses (PDF), bacterial spot is more of a problem for field tomatoes than for greenhouse tomatoes. Symptoms and management of bacterial spot are described briefly at Bacterial Spot of Tomato and Pepper (PDF). A more detailed version of this article is found at An Update on the Use of Copper Products for Managing Bacterial Spot of Tomato (Blog Post). This article will discuss why copper products have become less useful in the control of this important disease and options for managing bacterial spot of tomato. Copper products have been used for many years to help control bacterial spot of tomato. However, some strains of the bacteria that cause this important disease are resistant to copper—that is, the bacteria have mutated to a form that is no longer sensitive to copper. Some of[Read More…]

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