Protection of Grapevine Pruning Wounds against Eutypa lata by Biological and Chemical Methods

  • F. Halleen ARC Infruitec-Nietvoorbij (The Fruit, Vine and Wine Institute of the Agricultural Research Council), Private Bag X5026, Stellenbosch 7599, South Africa
  • P.H. Fourie Citrus Research International, P.O. Box 2201, Stellenbosch 7602, South Africa
  • P.J. Lombard Kelp Products (Pty) Ltd, PO Box 325, Simonstown, 7995 South Africa

Abstract

Eutypa dieback, caused by the fungus Eutypa lata, is a serious disease of grapevines that infects mainly through pruning
wounds. The aim of this study was to evaluate the in vitro efficacy of fungicides from various chemical groups against
E. lata, as well as the in vivo efficacy of the most effective fungicides and selected bacterial and fungal antagonists of
E. lata, in grapevine pruning wound protection trials. In vitro studies revealed that flusilazole, tebuconazole, benomyl,
fenarimol and myclobutanil were the most effective fungicides to inhibit mycelial growth of E. lata. Two field trials
were conducted, one subjected to artificial inoculation and the second to natural infection only. In the first, benomyl,
flusilazole and commercially available Trichoderma harzianum-containing products and an experimental Bacillus
subtilis strain were applied to fresh pruning wounds. Two Cabernet Sauvignon vineyards were pruned in August
2001 and 2002 and immediately treated and inoculated with a spore suspension of E. lata one day later. Isolations
were made from the treated pruning wounds after 12 months to assess the effectiveness of the treatments. The
fungicides benomyl and flusilazole were the most effective treatments, although the Trichoderma treatments T77 and
Trichoseal spray caused a significant reduction in E. lata infection. In a second trial, pruning wounds of Cabernet
Sauvignon, Sauvignon blanc, Red Globe and Bonheur were treated with the Trichoderma products Vinevax (=
Trichoseal spray) and Eco77 (= T77) in August 2005 and 2006, subjected to natural infection only and evaluated
after seven months. Vinevax and Eco77 not only reduced E. lata, but they also reduced the incidence of other
grapevine trunk disease pathogens.
Published
2016-12-12
Section
Articles