Abstract

In semiarid potato (Solanum tuberosum L.) production regions most potatoes are irrigated through sprinklers. Reduction of stress caused by hot, dry climates could improve tuber yield and quality. Folicote (Aquatrols Corp. of America, Pennsauken, NJ) is the common name for a 50% paraffin wax emulsion reported to reduce water loss and the daily water requirement of potatoes. This study was conducted to determine the feasibility of economically applying folicote with drop nozzles for increasing yield and improving chipping quality of the potato cultivar Atlantic. Using drop nozzles angled upward on each side of potato rows, a 4% concentration of folicote was applied at 20 and 40 gal/acre with a surfactant or a crop oil additive. This treatment significantly increased yields of U.S. no. 1 tubers between 2.25 and 3.25 in. (57–88 mm) in diameter by 10 to 31% in six field trials over 4 yr, 1989 to 1992. The number of tubers greater than 3.25 in. with hollow heart was reduced by as much as half. There were no effects on specific gravity, chip color, tuber rots, or vascular discoloration. There was no difference between the addition of a surfactant or a crop oil concentrate at 0.5%. In 1992, 2, 4, and 8% folicote applications were tested at 20, 40, and 80 gal/acre for increasing yields. The concentration of folicote in the spray solution played a more important role than the amount of folicote applied per unit of land area. The best overall treatment was 4% folicote applied in 40 gal/acre (374 L/ha) representing an approximate cost of $15/acre. The use of drop nozzles to apply folicote appears to increase quality and yield of chipping potatoes at an economically acceptable cost to growers.

Research Question

Heat stress decreases yield of chip quality potatoes and increases the incidence of hollow heart. The objective of this study was to evaluate the drop-nozzle application of folicote, a wax emulsion used as an anti-transpirant, to minimize the reduction in yield and quality of chipping tubers due to heat stress on the potato cultivar Atlantic. The addition of an oil vs. a surfactant, and the effect of gallonage and concentration were part of this study to determine if folicote use can be economical.

Literature Summary

Folicote reduces transpiration by forming a waxy film barrier on the leaf surface to inhibit the escape of water vapor through leaf openings. Yield increases due to folicote use have been reported for corn, sorghum, and several tablestock cultivars of potatoes. In previous studies on potatoes, however, folicote was applied to run-off or at over 100 gal/acre, which is not economical for potato production.

Study Description

Six trials were conducted between 1989 and 1992 in a semiarid potato production region in Nebraska. Plots were irrigated below recommended amounts. Folicote was applied once using drop nozzles on each side of plants between 3 July and 2 August at the onset of a week of high temperatures. In five trials (1989–1991), plants were treated with 4% folicote sprayed at 20 and 40 gal spray/acre (40 psi) with either a sticker or crop oil concentrate added to the spray. In the 1992 trial, 2, 4, and 8% folicote were compared at 20 and 40 gal/acre; 4% folicote also was tested at 80 gal/acre. Yield data were taken based on tuber size, and chip quality data (hollow heart, specific gravity, and chip color) were also taken on plot samples. Since there were no interactions between treatments and years, data from 1989 to 1991 were combined for analysis.

Applied Question

Will folicote applied at economical rates and gallonages increase chip potato yields and improve tuber chipping quality?

Folicote increased the yield of premium sized chipping tubers and decreased the number of tubers with hollow heart, an internal tuber defect which disqualifies a tuber for chipping (Fig. 1). These effects were achieved using less folicote per acre than previous reports, due to the use of drop nozzles that wetted the undersurface of leaves where most water loss occurs during hot, dry weather. Folicote at 4% improved premium yields, tubers between 2.25 and 3.25 in., more consistently at different gallonages than higher and lower concentrations (Fig. 2). In earlier studies, the need for an additive was demonstrated, but there were no major differences detected in this study between a sticker and a crop oil. Specific gravity was also increased from 1.086 to 1.088 with 4% folicote at 20 gal/acre, and there was no effect on chip color.

Fig. 1

Changes in the yield of >2.25-in. tubers cv. Atlantic without hollow heart (premium yield) and in the number of >3.25-in tubers with hollow heart.

 

Fig. 2

Increase in premium yield (2.25- to 3.25-in. tubers) due to 2, 4, and 8% folicote applied at 20, 40, and 80 (for 4%) gal/acre applied with drop nozzles to the potato variety Atlantic.

 

Copyright © 1995. . Copyright © 1995 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, 5585 Guilford Rd., Madison, WI 53711 USA