Two low-dose dicamba exposure trials were conducted on container-grown peach trees in Fayetteville, AR. Peach trees were ‘July Prince’ scions grafted onto ‘Guardian’ rootstock, were transplanted into 19-L containers, and received experimental dicamba treatments in each year. Container trials were initiated in 2020 and repeated on new trees in 2021. In the repeated application trial, dicamba was applied at 5.6 g ae ha−1 (1/100X field rate) in five sequences: an untreated control receiving no herbicide, one treatment receiving only an initial application, and three treatments receiving an initial application plus sequential applications at the same rate occurring at 14 d, 28 d, and 14 d + 28 d after initial treatment (DAT). A separate trial assessed peach tree responses to dicamba applied at 11.2 g ae ha−1 (1/50X field rate) using a selection of nozzles with differing droplet spectrum characteristics: Turbo TeeJet® induction nozzle TTI11002, air induction turbo TwinJet® nozzle AITTJ60-11002, air induction extended-range (XR) TeeJet® nozzle AIXR11002, XR TeeJet® flat-fan nozzle XR11002, and XR TeeJet® flat-fan nozzle XR1100067. Peach tree height, tree cross-sectional area, and leaf chlorophyll content were not reduced in response to any sequence of dicamba application or nozzle selection. Repeated applications of dicamba at a 1/100X rate did not increase peach injury after 28 DAT. By 84 DAT, no effect of nozzle type on peach tree injury was discernable, and all treatments caused below 4% injury. No dicamba or dicamba metabolites were observed in leaf samples collected at 14, 69, or 85 DAT from trees treated with XR1100067 or in untreated controls. While peach tree injury was observed throughout the experiment, dicamba residues were detected consistently only in 2020 from leaf samples of trees treated with dicamba at a 1/50X rate using TTI1102, AITTJ60-11002, AIXR11002, and XR11002 nozzles.

A semi- and high-density apple and peach orchard was established at Blacksburg, VA. Starting 1 yr after transplanting, tree rows were treated with paraquat, 2,4-D, or amitrole plus simazine for 4 yr. Thereafter, diuron, simazine, or terbacil was applied in conjunction with paraquat or glyphosate. During the 12th growing season, young trees planted between existing trees failed to make proper growth. Oat bioassay of soils collected from treated rows revealed that the tree row topsoil (0 to 7.5 cm) produced less oat biomass than did deeper row soils (to 30 cm) or soils of corresponding depths from adjacent non-treated tall fescue sod alleyways. Poor growth of trees may have been related to other factors (competition from older trees, drought conditions, etc.) since herbicide residues in the upper 7.5 cm would have little effect on tree roots below this depth. After 3 yr the trees developed normally. Tree rows became heavily infested with weeds 1 yr following cessation of 23 yr of consecutive herbicide treatments.

Fruit trees in orchards of the mid-Atlantic region of the United States are often planted in vegetation-free rows alternating with grass alleys. Grass managed to suppress weeds but to compete minimally with fruit trees may be an alternative to herbicide and tillage. This research was conducted in the greenhouse and field to assess five different grasses that may suppress weeds without reducing yield of fruit trees. In the greenhouse with high seeding rates, red fescue competed more effectively than did chewings fescue, tall fescue, and perennial ryegrass with three weeds (damesrocket, cornflower, and chicory). However, with reduced seeding rates, similar to rates used in the field, grass competitiveness with weeds was similar between red fescue, tall fescue, and perennial ryegrass. Similar results were obtained during a 4-yr field experiment; roughstalk bluegrass competed least effectively with weeds but the other four grasses provided similar weed suppression—generally providing as much weed suppression as traditional herbicides. None of the candidate grasses significantly reduced yields of 10-yr-old apple and peach trees, although fruit size was affected by some grasses. The grass that was least suppressive of yield, roughstalk bluegrass, was the least effective in controlling weeds. Annual mowing in combination with four of the grasses tested is one option to manage the orchard floor with reduced herbicides, but fruit size may decrease.

In this study, the basic biology of and artificial rearing techniques for Bactrocera pyrifoliae (Drew and Hancock), a pest of peaches and plums in high-elevation areas of northern Vietnam and Thailand, were investigated for 5 years. Bactrocera pyrifoliae was found only between elevations of 1000 and 1500 m, heavily infesting peaches and plums from early June to harvest in mid-July. The durations of the egg, larval and pupal stages were determined under controlled environmental conditions in the laboratory, indicating that B. pyrifoliae is a multivoltine species. Larvae were successfully reared on a carrot and corn powder-based diet. Determinations of the appropriate adult density in colony cages, and also optimal temperature conditions for holding adults, were made. Bactrocera pyrifoliae performed better when the temperature was lowered during the night, as would be expected for a species adapted to temperate-like environments. Interestingly, adults originating from field-collected pupae emerged with a 3:1 female-biased sex ratio. Laboratory colonies, by generation seven, appeared to exhibit signs of inbreeding depression and required periodic incorporation of wild insects to restore egg hatch. To develop sound management techniques for populations of B. pyrifoliae infesting peaches, alternate commercial and native hosts infested outside the peach and plum fruiting season must be identified or some form of overwintering mechanism such as reproductive diapause be discovered. Documentation of mating behaviour in the field (a key to developing efficient traps), improvement in fertility in laboratory colonies, and eventually sterile insect technique-based integrated pest management for pest population management in the expanding low-chill temperate fruit-growing areas of northern Vietnam are also needed.

Serious side effects from the conventional use of traditional chemical pesticides for routine arthropod pest management have prompted the investigation and development of alternate strategies for the minimization of pest damage. Insect sex pheromones have been proposed as a potential group of alternative control agents for over twenty years. The possible uses of these substances for insect control are discussed and factors influencing their development for pest management are presented. The scientific research and commercial development of oriental fruit moth mating disruption is presented as a case study for the commercialization of this approach. Advantages and limitations of pheromone-based control tactics are presented. Mating disruption technology is starting to find its place in a number of diverse cropping situations. The use of pheromones for pest control promises to be an important component of the ongoing challenge to develop alternatives that may help to solve major environmental and human health problems associated with chemical pesticide use in agriculture.