From the laboratory to the field: litter management for control ofBotrytis cinereain boysenberry gardens

Abstract

From the laboratory to the field: litter management for control of Botrytis cinerea in boysenberry gardens. Abstract -- Introduction. Litter on the ground is a primary source of Botrytis cinerea inoculum in boysenberry (Rubus hybrid) gardens. The effect of litter management on primary inoculum pro- duction, and flower and berry infections was determined. Materials and methods. A series of expe- riments ranging from laboratory to large-scale field evaluations were conducted in New Zealand during 1997-2002 to evaluate litter management options for control of B. cinerea. The laboratory trial investigated the effect of litter size (shredded vs. unshredded litter) and debris amendments on tissue degradation and B. cinerea colonization. The field trial (four sites) investigated the effect of litter amendments (compost, urea and fungicide) and piling litter on B. cinerea sporulation. In the 4-year commercial-scale study (three properties), the effect of litter treatment (piling, compost and microbial extracts/suspensions) on primary inoculum, flower and berry infections was assessed. Results and discussion. The laboratory trial showed that bark + sewage sludge compost amend- ment enhanced litter decomposition and reduced B. cinerea sporulation on infected tissue after 8 weeks. The field trial indicated that piling of shredded boysenberry debris was more important than litter amendments in reducing the amount of B. cinerea harbored within the litter. Commercial field-scale evaluation of litter management options verified that piling of shredded litter is the most important step in B. cinerea inoculum control from debris. It also showed that microbial litter amend- ments (compost, solutions or extracts) can be beneficial. While B. cinerea inoculum control also reduced the amount of flower infections, berry infections at harvest were not affected, indicating that other sources of B. cinerea inoculum contribute to berry infection post-flowering.