Apple Storability as Influenced by Tufted Apple Bud Moth Injury, Orchard Fungicide Programs, and Horticultural Factors

Abstract

As public pressure increases to reduce the use of agricultural chemicals, the effects of lower chemical dosages in the orchard on fruit storability must be determined. Based on both artificial and natural damage, minor tufted apple bud moth (TABM) injury (<10 mm aggregate diameter) did not cause significant loss during controlled-atmosphere (CA) storage. However, damage in excess of 10 mm often caused significant weight loss and decay. Damage occurring closer to harvest caused more loss of quality than earlier damage (i.e., during July and early August). Forty percent of apples damaged 1 week before harvest decayed during storage. Several orchard fungicide spray programs were studied, and in 1993–94, all of the tested programs adequately controlled both fruit blotches and rots, and few storage rots developed. These diseases were light in 1993 due to low rainfall during the summer months. Development of the summer diseases were somewhat higher in 1994, but similar fungicide programs provided adequate control of the complex at harvest. Apples inoculated with P. expansum (punctured with a nail) decayed less when stored in 3% CO2 than in 0% CO2 (at both 1% or 2.4% O2). Decay of `Golden Delicious' caused by P. expansum inoculation increased with later harvest (twice as much decay in fruit harvested 14 Oct. than in fruit harvested 23 Sept.–7 Oct.).