Hulless Barley Response to Ethephon Application

Ethephon [(2‐chloroethyl) phosponic acid] is commonly used in mid‐Atlantic barley production to reduce plant height and lodging, but is known to reduce grain yield and test weight in some barley cultivars. Management practices that produce high yield and good grain quality in traditional mid‐Atlantic winter barley have yet to be evaluated for hulless barley. This research examined response of three winter hulless barley genotypes to ethephon plant growth regulator (PGR) and provides recommendations for appropriate PGR rates. Ethephon applied at 2.5 oz a.i./acre resulted in decreased plant height (8.3 inches) and lodging index (1.2 units). With higher rates, a trend toward continued decreased height and lodging was seen even when differences were not significant. Grain yield was decreased by an average of 20 bu/acre in four of 15 site year‐genotype combinations. Grain test weight was increased in one instance but impacts of ethephon varied by genotype, which may warrant further study. Labeled rates of ethephon are appropriate for application to a range of hulless barley cultivars but rates above 2.5 oz a.i./acre should be avoided unless severe lodging is anticipated. Ethephon application should occur only when moisture and temperature are favorable for plant growth and not when the crop is under stress.