10 articles tagged "Transplant Production".

These tomato plants are exhibiting epinasty or a downward growth of the leaves in response to ethylene produced from a malfunctioning heater in a greenhouse. The topmost leaves are growing normally because the plants were removed to a separate greenhouse after exposure to ethylene. (Photo by Dan Egel).

Almost every year, I have a greenhouse tomato grower or two call me about tomato plants that are distorted and don’t seem to be growing right. The problem often turns out to be ethylene damage. This year, I have decided to write an article about it before I get those calls. Tomato plants with ethylene damage often have leaves that are curled down and stems that are twisted (Figure 1). Stems or leaves that are curled downwards are said to have 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; however, other crops may also show ethylene damage. The tomato plants in figure 1 also have yellow seed leaves. Ethylene damage does not include yellowing.[Read More…]


Gummy Stem Blight – this fungal disease causes dark brown leaf spots, however, the diagnostic feature of this disease is the water soaked lesion that is often formed under one of the seed leaves (cotyledons). Such lesions often start at the point where the seed leaf joins the stem (hypocotyl) and do not extend to the soil line (Figure 1). In time, these lesions turn a light brown in color and appear ‘woody’. If one inspects the woody stem closely, it is possible to see dark specks imbedded in the stem—these are fruiting bodies of the fungus and will exude numerous spores when wet. Gummy stem blight affects both cantaloupe and watermelon. The fungus that causes gummy stem blight may be seed borne. The fungus may also survive on the residue left on contaminated transplant trays, the greenhouse floor or bench. Gummy stem blight may spread rapidly from plant to[Read More…]


A grafted tomato plant growing in a high tunnel. (Photo by Wenjing Guan)

​You might have heard about tomato grafting, or you might even already have tried the new technique. Yes, it has multiple benefits: control of soilborne diseases, enhanced tolerance to abiotic stresses, and increased productivity. It works for some growers, but not all. Why? There are several reasons. First, effects of grafting on controlling soilborne diseases depend on the presence of the disease that the rootstock is designed to control. For example, grafting might not be very helpful for white mold, because current commercial rootstocks do not have resistance to white mold. However, grafting might work if the primary problem is Fusarium crown and root rot, as most commercial tomato rootstocks have resistance to this disease. With that said, it is very important to look at the disease resistance profile before deciding on the rootstocks. Second, grafting effects on improving yield depend on factors such as scion and rootstock cultivars, cultural[Read More…]


​Samples in plug trays, as well as unrooted and rooted cuttings, and plants in pots require extra care when they are packaged for submittal to a diagnostic lab. Before you mail the next sample, please take a few minutes to review these suggestions for packaging and submitting samples. This will help preserve the integrity of the sample during shipment and increase the likelihood of a more accurate diagnosis. Plugs – keep them in the tray. If possible, do not remove the plugs from the plug tray. Submitting either an entire tray or cutting off a section of the tray helps maintain the integrity of the plants (Figure 1). Secondary decay often occurs when soil is allowed to come in contact with the foliage, interfering with accurate diagnosis. When possible, submit at least 5-10 cells with plugs. This provides the diagnostician with ample material for microscopic observation, culturing, and virus testing[Read More…]


This watermelon transplant has a water soaked area just under the seed leaves

Most watermelon growers are in the process of placing transplants in the field. I have received several commercial samples of transplants still in trays prior to out-planting. The two diseases I have observed so far are gummy stem blight and bacterial fruit blotch. Below, I discuss these two diseases as well as management options. Gummy stem blight on transplant seedlings may be recognized by the watersoaked area of the stem (botanical term:  hypocotyl) as shown in Figure 1. The watersoaked area may eventually turn brown and woody.  A closer look at the woody area may reveal the small, dark fungal structures of the gummy stem blight fungus (Figure 2). The true leaves of watermelon transplants may also be affected. The fungus that causes gummy stem blight (Didymella bryoniae) may survive in crop debris, thus overwintering in the field from year to year. This fungus may also survive in seed. It is also possible for the fungus to[Read More…]


Waterwheel transplanters are commonly used for vegetables on plastic-covered beds. (Photo by K. Freeman)

Getting seedlings from the transplant tray into the field is essential for a good crop (Figure 1). Healthy transplants treated well will quickly establish themselves in the field, setting the foundation for a productive crop.​  Here I offer some suggestions for successful transplant establishment. Harden transplants by exposing them to higher light, cooler temperature, and slightly drier conditions than during transplant production (Figures 2 and 3). One goal of hardening is to slow growth of the seedlings and increase their stored energy. A second aim is to acclimate the plants to the field environment. A properly hardened plant will recover from the stresses of transplanting more quickly and begin to grow sooner than a plant that has not been hardened. Seedlings are commonly hardened by putting them outside in a partially shaded and protected location, often on a wagon so they can be moved indoors if low temperatures or high[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…]


Unit heaters that aren’t properly maintained can be a source of air pollution that harms seedlings. (Photo by E. Maynard)

Transplant production will soon begin in earnest if not already underway. It is sensible to check the greenhouse heating system before starting production to make sure it works and won’t pollute the air in the greenhouse. This checklist for gas or propane-fire unit heaters highlights some of the major points. If you are not familiar with the system a service technician can help. General Maintenance. Check for physical damage; Remove any obstruction in vent and exhaust systems; Make sure components are supported properly and securely. Fans and Blowers. Lubricate as needed; Check for smooth operation; Inspect for physical damage; Adjust belts as needed; Check connections to electrical power. Heat Exchangers and Burners. Inspect exchanger closely for cracks or corrosion where air-polluting gases can escape; Clean inside tube surfaces if required; Inspect for dark discoloration on metal which may be a sign of overheating and if found, investigate cause; Clean gas[Read More…]


Flats of cabbage transplants are supported a few inches from floor of greenhouse

Many Indiana vegetable crops begin life as transplants. If lack of nutrients, lack of light, disease, or other problems slow growth during this stage it may reduce establishment success and/or growth and yield in the field or high tunnel. Good management of the following factors should lead to healthy transplants (see Figure 1). Time. Don’t seed transplants too early. Overgrown transplants are difficult to manage. If they get so root bound and shaded by other plants in the same flat that growth stops it will take them longer to resume growth in the field. They may become weakened and more susceptible to disease in the transplant tray and field. The ideal time depends on the crop and cell size, as well as the growing temperature. For ease of transplanting the finished transplant should have a well-developed root system that holds the root ball together, a sturdy stem, and be of[Read More…]


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