Field evaluation of biocontrol agents against black-foot and Petri diseases of grapevine

BACKGROUND Black-foot and Petri diseases are the main fungal diseases associated with young grapevine decline. Two field experiments were established to evaluate the preventive effect of two potential biocontrol agents (BCAs), that isStreptomycessp. E1 + R4 andPythium oligandrumPo37, and three BCA-commercial products containingTrichoderma atrovirideSC1,Trichoderma koningiiTK7 andPseudomonas fluorescens + Bacillus atrophaeuson fungal infection in grafted plants and plant growth parameters. RESULTS The effectiveness of some BCA in reducing the incidence and severity of both diseases was dependent on the plant part analyzed and the plant age. No single BCA application was able to control both diseases.Streptomycessp. E1 + R4 were able to reduce significantly the infection of the most prevalent black-foot disease fungi whileP. oligandrumPo37 andTrichodermaspp. were able to reduce significantlyPhaeomoniella chlamydosporaandPhaeoacremonium minimum(Petri disease) infection. BCA treatments had no effect on the shoot weight, and root weight was significantly lower in all BCA treatments with respect to the control. CONCLUSIONS The combination of the disease-suppressive activity of two or more beneficial microbes in a biocontrol preparation is required to prevent infection by black-foot and Petri disease fungi in vineyards.