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A preliminary study examining soil microbiology and nutrient dynamics in year three of a peach orchard at the Sandhills Research Station‎, North Carolina, USA found that maintaining a 3.6-m vegetation-free strip in the tree row reduced microbial biomass and associated activities in the soil, compared with a 0 m strip, and that the use of under tree micro-sprinkler irrigation increased peach root colonization by endomycorrhizal fungi as well as microbial biomass and associated activities. The current study was conducted in years four and five of that orchard and examined vegetation-free strip widths of 0, 1.2, 2.4, and 3.6 m, with and without irrigation, to determine their effects on endomycorrhizal fungal colonization of peach roots, soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil microbial respiration (SMR), and net nitrogen mineralization (NNM). There were no significant differences between treatments for endomycorrhizal fungal colonization or MBC by year four. The 3.6 m vegetation-free strip had the lowest MBN and SMR in year four with no significant difference between strip treatments in year five. NNM decreased with greater vegetation-free strip widths in years four and five. Irrigated plots had significantly higher MBN and lower SMR in the spring of year five with no other significant differences due to irrigation. These important findings show that under standard commercial management of a bearing peach orchard there is little impairment of soil ecological function in the rhizosphere, allowing for maximum peach yield and quality while supporting the health of trees and soil.

Biochar offers several benefits as a soil amendment, including increased soil fertility, carbon sequestration, and water-holding capacity in nutrient-poor soils. In this study, soil samples with and without biochar additives were collected for two consecutive years from an experimental field plot to examine its effect on the microbial community structure and functions in sandy soils under peach-trees (Prunus persica). The four treatments evaluated consisted of two different rates of biochar incorporated into the soil (5%, and 10%, v/v), one “dynamic” surface application of biochar, and a 0% biochar control. Fatty acid methyl ester (FAME) analysis was used to assess the microbial community structure, and enzyme activities involved in C, N, P, and S nutrient cycling were used as a means of assessing soil functionality. Total FAME and bacterial indicators increased by 18% and 12%, respectively, in the 10% incorporated and 5% surface applied treatments. Biochar applications increased β-glucosaminidase and arylsulfatase activities, 5–30% and 12–46%, respectively. β-glucosidase and acid phosphatase activities decreased by approximately 18–35% and 5–22% in the 0–15 cm soils. The overall results suggest that biochar’s addition to the sandy soils stimulated microbial activity, contributing to the increased mean weight diameter (MWD), C sequestration, and consequential soil health. The changes in microbial community structure and functions may be useful predictors of modifications in soil organic matter (SOM) dynamics due to the long-term application of pine biochar in these systems.

Biochar may enhance soil health in sandy soils under peach [Prunus persica (L.) Batsch] tree production. A study was initiated in the Sandhills of North Carolina by applying pine‐biochar at two different rates (5 and 10%, v/v) and types of application (incorporation to 30 cm [‐Inc] and surface [‐Sur]) in 2017. Soil organic matter (SOM) dynamics was assessed via soil organic carbon (SOC), total nitrogen (TN), permanganate‐oxidizable carbon (POXC), aggregate fractions (macro‐, micro‐aggregates, and clay + silt particles), and enzyme activities (CNPS activity) at 0–15 and 15–30 cm in 2018 and 2019. After the first year of pine‐biochar application, POXC decreased in all biochar treatments, SOC was higher in the 10%‐Inc treatment, whereas CNPS activities and macroaggregates were highest in the 5%‐Sur compared with the non‐treated control. These results suggest early changes in SOM dynamics and biogeochemical cycling and have the potential to guide producers with the long‐term application of pine‐biochar to sandy soils.

Many of the apples (Malus ×domestica) grown in the southeastern United States are sold to consumers through direct farm markets and roadside stands. Fruit in these markets may be exposed to high temperatures (>68 °F), which cause the fruit to ripen quickly, limiting their shelf life and consumer appeal and increasing their susceptibility to decay pathogens. Studies were undertaken in 2009 and 2010 to determine the effects of a 1-μL·L−1 postharvest 1-methylcyclopropene (1-MCP) treatment on the maintenance of flesh firmness and the incidence of rots in fruit held at elevated temperatures for up to 8 weeks. 1-MCP-treated fruit of three apple cultivars (Ginger Gold, Gala, and Golden Delicious) held in three retail farm markets in the southeastern United States maintained their firmness for 3 to 5 weeks. The firmness of non-treated ‘Ginger Gold’ fruit declined to less than 12 lbf after 1 week in each market, whereas the firmness of treated fruit remained greater than 16 lbf after 3 weeks. Treated ‘Gala’ fruit maintained their firmness at 14 lbf during 4 weeks in each farm market, whereas the firmness of non-treated fruit declined to less than 12 lbf after 2 weeks. The firmness of non-treated ‘Golden Delicious’ fruit declined to less than 12 lbf after 1 week in each farm market, whereas treated fruit maintained their firmness for up to 4 weeks. ‘Golden Delicious’ fruit treated with 1-MCP exhibited almost no loss of firmness during 4 weeks at 32, 50, or 70 °F, or even up to 8 weeks at 32 or 50 °F. The incidence of fruit rots increased with temperature, and 1-MCP reduced the incidence of fruit rots after 4 weeks at 70 °F in 2009 or after 8 weeks at 70 °F in 2010. These data show that 1-MCP may be of great benefit to producers who sell their fruit directly to the consumer by delaying the loss in firmness and reducing the incidence of rots in fruit kept at elevated temperatures.

An experiment was conducted at one location in 1999 and two locations in 2000 to determine the critical weed-free period for peach in North Carolina. The cultivars for the three locations were ‘Contender’, ‘Norman’, and ‘Summerprince’. Weed-free intervals of 0, 3, 6, 9, 12, and 15 wk after peach tree bloom were established. Paraquat at 1.1 kg ai/ha plus nonionic surfactant at 0.25% v/v was applied every 10 d, after treatments were initiated at peach bloom, to maintain weed-free plots. Large crabgrass, hairy vetch, and smooth crabgrass were the primary weeds in Contender. Horseweed, smooth crabgrass, and large crabgrass were the primary weeds in Norman. Bermudagrass, smooth pigweed, and common lambsquarters were the primary weeds in Summerprince. No differences in trunk cross-sectional area were observed between the weed-free periods. Maintaining the orchard floor weed-free for 12 wk after peach tree bloom resulted in the greatest fruit size (individual fruit weight and diameter), total yield, and fruit number.

White clover is a weed in apple orchards that competes with the crop; also, flowers of this weed are unwanted attractants of honey bees at times when insecticides, which are harmful to these pollinators, are being applied. In 1997 and 1998, white clover flower head and plant control by clopyralid alone and with 2,4-D and apple tolerance to these herbicides were determined. Treatments consisted of clopyralid at 0.10 and 0.21 kg ae/ha, 2,4-D at 1.1 kg ae/ha, and 2,4-D at 1.1 kg ae/ha plus 0.03 or 0.05 kg ae/ha clopyralid, which were applied 2 wk before full apple bloom and 2 wk after full apple bloom, and a nontreated check. No crop injury occurred with any treatment. All herbicide treatments provided some white clover control and flower head suppression. No differences in white clover bloom reduction were observed through May among treatments containing clopyralid. As summer progressed, the effect of clopyralid rate became more apparent. Clopyralid at 0.21, regardless of application time, provided 99% vegetative control and 100% flower head reduction through July. Clopyralid plus 2,4-D controlled white clover better than 2,4-D alone. However, vegetative control and flower head reduction with clopyralid at reduced rates (0.03 or 0.05 kg ae/ha) plus 2,4-D were not acceptable (76% or less and 78% or less, respectively). Thus, clopyralid at 0.10 and 0.21 kg ae/ha will be necessary for acceptable white clover vegetation control and flower head reduction.