Potential Options for Managing Frost-damage in Vegetable Crops (Coolong and Dutta)
Because of the potential for an upcoming frost this week on newly planted vegetable transplants we are sure you are getting questions from concerned growers. I have attached a link to a publication on frost and freeze protection https://secure.caes.uga.edu/extension/publications/files/pdf/B%201479_1.PDF that, while heavily focused on fruit, has several sections applicable to veggies. A few key points for veggies:
· Plastic mulch will usually get you about 2 oF of additional protection when the plant canopy is very close to the plastic (as it is now) and it is sunny during the day.
· Copper Sprays: Often used by growers with the idea of killing any ice nucleating bacteria on the leaf surface to prevent ice formation. This has been shown to work in controlled studies, but in the field there are often other factors that limit the effectiveness. One of which is that dirt and dust on the leaves can also be a source of ice nucleation. Many growers spray copper before a frost and in general it isn’t harmful. However, in some cases (watermelon), young seedlings (1 week or 1.5-week-old) can be susceptible to show phytotoxic response to copper.
· Irrigation: Irrigating for freeze protection is mostly used on fruit and is covered in the attached publication. Pivot irrigation will not work for freeze protection BUT moist soil will tend to retain some heat from the day and can give a grower a little protection in the evening. If the soil is already wet then additional irrigation won’t help, but if it is dry, then adding some moisture to the soil can help give some protection.
· Other sprays: A variety of other sprays (ie. Vapor Guard) are sold on the market for frost protection and the limited number of studies done on them indicates that they do not work. Here is the study done on tomato and pepper: Perry, K.B., Bonanno, A. R., & Monks, D.W. (1992). Two putative cryoprotectants do not provide frost and freeze protection in tomato and pepper. HortScience 27:26-27.
· Row cover are the most effective option, but not economical for the large acreages we are working with.