A Topical Spray to Enhance Plant Resistance to Cold Injury and Mortality

Abstract

<jats:p>A novel topical spray was developed to increase resistance to both cold damage and cold mortality in plant foliage, flowers, and fruits. In environmental chamber experiments, application of the spray to monocot and dicot foliage lowered the environmental temperatures associated with the first onset of cold injury and with cold mortality from 2.2 to 9.4 °F, compared with controls sprayed with tap water, over an effective temperature range (depending on species) of ≈0 to 32 °F. The threshold temperature for flower mortality was lowered from 2.2 to 3.2 °F depending on species. Mature fruit suffered significantly less freeze damage when pretreated with the spray formulation. The spray is composed of ingredients that are non-toxic to plants, humans, and other animals. The patent-pending formulation has been commercialized under the trade name FreezePruf.</jats:p>

Does FreezePruf Topical Spray Increase Plant Resistance to Freezing Stress?

“…TOMATO FRUIT. Franko et al (2011) indicated FreezePruf increased the percentage of viable tomato fruit by %50% compared with controls exposed to -3.9°C for 2 to 3.5 h. Based on that report, a preliminary experiment was conducted to determine whether the supercooling duration of tomato fruit held at -3.9°C was increased by FreezePruf. However, only one out of 40 fruit exhibited an exotherm during 24 h at -3.9°C.…”

“…The authors examined the effects of dimethyl sulfoxide, proline, polyvinylpyrrolidone, a mixture of amino acids, and a solution containing glycerol and vitamin E. The only treatment that increased the survival percentage after exposure to -4°C for 1 h was glycerol plus vitamin E. It was interesting to note that protection was not strictly a colligative effect since 0.7 M glycerol was optimum, but higher or lower concentrations had survival percentages that were not different from the control. Although Moratiel et al (2011) did not examine FreezePruf, glycerol (5 mM) is one of the components (Franko et al, 2011).…”

“…Stolons, which were directly treated with FreezePruf, did not exhibit increased freeze tolerance compared with controls sprayed with water. In addition to treatment 24 h before assay (Franko et al, 2011), bermudagrasses in the present report were also treated 1 week before lowtemperature exposure to allow for translocation and promotion of acclimation. Although no freeze protection benefit was observed in bermudagrass not exposed to acclimating temperatures, it is possible that FreezePruf could augment acclimation in conjunction with low temperature-induced tolerance.…”

“…1 Franko et al (2011) suggested hypothetical mechanisms of action may include colligative freezing point depression, noncolligative membrane stabilization, stimulation of proline production, cell wall reinforcement, and reduction in water loss from leaves. A report by the developer indicated that up to 5°C (equivalent to one U.S. Department of Agriculture plant hardiness zone) protection was provided to flowers, leaves, and fruit (Franko et al, 2011). While the level of protection varied with plant material, a 5°C increase in freeze avoidance or tolerance would be biologically and economically significant.…”

“…FreezePruf is a commercially available product recently marketed by the Liquid Fence Company (Broadheadsville, PA) to improve both freeze avoidance and tolerance. FreezePruf contains polyethylene glycol, potassium silicate (AgSil 25; PQ Corp., Valley Forge, PA), glycerol, silicone polyether surfactant (Silwet L-77; Setre Chemical Co., Memphis, TN), and a bicyclic oxazolidine antidessicant (Wilt-Pruf; Wilt-Pruf Products, Essex, CT) (Franko et al, 2011). Approved for publication by the Director, Oklahoma Agricultural Experiment Station.…”