Biochar Amendments As an Alternative to Manage Peach Replant Disease

The present study explores the effects of biochar as a soil amendment to alleviate replant disease (RD) in peach trees. The use of RD tolerant rootstocks has become a valuable alternative to manage replant in apple orchards; however there are currently no RD tolerant rootstocks available for stone fruits, and conventional management of this soilborne disease with soil fumigants is limited due to the global phase-out of methyl bromide. Exploring new alternatives to mitigate the effects of RD through the use of organic amendments may be an environmentally sound and sustainable solution to manage RD in stone fruits. The use of biochar as a soil amendment to improve soil fertility has generated great interest all over the world, and its effects on soil biological properties have shown promising results on the control of soilborne diseases. The objective of the present study was to evaluate the effect of biochar on peach tree growth; biomass production and nutritional status under replant conditions. Peach trees were grown in pot in a greenhouse under 4 soil treatments: soil collected from a peach replant site (control), sterilized soil (sterilized), and biochar-amended soil at 10 and 20% (v/v) (low biochar and high biochar, respectively) all from the same peach replant site. Tree growth was measured weekly by recording trunk diameter increase. A subsample of trees were harvested at 11, 22 and 33 weeks after planting and total above and below ground biomass production was recorded for each date. Soil, foliar, and root samples were collected at each harvest date and were analyzed for nutrient content. Results showed significantly higher above and below ground biomass production in the biochar and sterilized soil treatments compared to the control. During the final harvesting date, soil nitrogen concentration was greater in the high biochar treatment, and foliar magnesium concentrations were significantly higher in both biochar treatments for all harvesting dates. Carbon content of first and second order roots was significantly higher in the high biochar treatment compared to the control. Based on the results of this study, applications of biochar to replant soils could alleviate RD in peach trees.