ARE FLOWERING PLANTS TABOO IN PEACH ORCHARDS?

Abstract

It is generally recommended that broadleaf plants in and around peach orchards must be controlled to minimize damage from stink bugs (Pentatomidae) and plant bugs (Lygus spp.). In research orchards located in West Virginia, USA, I have been growing peach trees as a monoculture or interplanted with apple, with and without the presence of broadleaf flowering plants. The flowering plants were used to enhance biological control of peach and apple insect pests. For two years, 1999 and 2000, damage to fruit by stink bug and plant bug was not significantly different in orchards with flowering plants and reduced insecticides as compared with an insecticide treated check orchard with just grass row middles and scattered broadleaf weeds. I suggest that vigorous, flowering broadleaf plants in peach orchards are more attractive hosts for stink bugs and plant bugs than are the peach fruit, and their presence can reduce damage by these insects thereby reducing the need for insecticide applications through early and mid-summer. INTRODUCTION A major barrier to implementing more intensive integrated pest management of peach (Prunus persica (L.) Batsch) in the eastern United States is the difficulty of monitoring and controlling stink bugs and plant bugs (Brown et al., 1999). These insects cause catfacing damage, a disfigurement of the fruit making it unmarketable, if they feed on the fruit prior to pit hardening (Polk et al., 1995). Later feeding, primarily by stink bugs, can cause a depressed corky or water-soaked region on the fruit where feeding occurred and gum droplets may form (Polk et al., 1995). Control of stink bugs and plant bugs is generally done by using a calendar based cover spray schedule to maintain a protectant residue on the fruit (Pennsylvania State University, 2000). It is also recommended that broadleaf weeds in and around peach orchards be removed to reduce stink bug and plant bug damage (Polk et al., 1995; University of California, 1999; Pennsylvania State University, 2000). Killian and Meyer (1984) showed a significant reduction in catfacing damage to peach in herbicide treated compared with non-herbicide treated orchards. In a research orchard in eastern West Virginia, USA, I have been growing broadleaf flowering plants in peach orchards to increase biodiversity with a goal of enhancing biological control. Here, I report on the effect of these flowering plants on stink bug and plant bug damage to the peach fruit. MATERIALS AND METHODS Experimental Design Four 0.5 ha orchards were planted in April, 1997, at a density of 560 trees/ha, with peach ('Loring'/'Lovell'), apple ('Granny Smith'/EMLA 26 and 'Royal Empire'/M9/EMLA 111), pear ('Buerre Bosc'/'Bartlett' and 'Seckel'/'Bartlett'), and sweet cherry ('Emperor Francis'/'Mazzard' and 'Ulster'/'Mazzard') in Jefferson Co., WV. For the first two years, ground cover management was identical in all four blocks with an herbicide strip maintained in the tree rows, primarily with glyphosate and paraquat. Alternating strips of the following flowering annual companion plants were planted adjacent to the tree rows in two orchards in May 1999 and 2000: buckwheat (Fagopyrum esculentum), dill