A successful tobacco season begins in the greenhouse and transplant production is off to a good start this season. With this in mind, cold injury is a common occurrence when growing transplants during the winter in a greenhouse. Cold injury can be noticed in plants sporadically throughout the greenhouse or can be confined to cold spots within the greenhouse. If you notice tobacco seedling leafs cupping upward, then this can be a sign of cold injury to greenhouse grown transplants.
Another thought to keep in mind, when skies are overcast and cloudy, the risk is greater for salt injury to occur during the initial germination stage. For fertilizer salts to acuminate, you need high temperatures, low humidity, and excessive air movement. This causes water evaporation from the surface of the soil and ultimately causes fertilizer salts accumulation in the top layer of growing medium. Be on the look out for salt accumulation in the upper ½ inch of growing medium. By using a calibrated conductivity meter, tobacco transplant growers can monitor salt levels. They not only can be used for monitoring salt levels in the growing medium, they can also monitor fertilizer salt levels in the float water.
Be sure to maintain a difference between day and night temperatures in order to keep from having a constant temperature because that could reduce the stand. Once you have a good stand, you can drop the temperature at night no lower than 55 degrees Fahrenheit to help save fuel.
A few other things to consider with producing tobacco transplants, is to maintain healthy plants. Monitor plants for nutrient deficiencies such as boron. Diseases always manage to appear in some form or fashion. Monitor transplants for rhizoctonia, sclerotinia, pythium, and bacterial soft rot.
Begin mowing plants when plant height is 2-2.5 inches above the bud. It is recommended to mow every 3-5 days no closer than 1-1.5 inches above the bud. Be sure to dump clippings at least 100 yards from the greenhouses to potentially minimize and reduce disease/pest problems. It is always a good practice to clean and sanitize mowers with a 50 percent bleach solution between mowing beds to minimize the spread of disease.
Della King is an extension agent with the Sampson County Cooperative Center specializing in field crops.