INTEGRATED LEAF REMOVAL AND FUNGICIDES APPLICATION FOR BETTER CONTROL OF GRAPES BUNCH ROT
INTEGRATED LEAF REMOVAL AND FUNGICIDES APPLICATION FOR BETTER
CONTROL OF GRAPES BUNCH ROT
A HEGAZI HASSAN
l Horticulture Department, Faculty of Agriculture, Mansoura University, Egypt
Background and objectives
<1> Botrytis cinerea 1> causing bunch rot of table grapes is especially severe in Northern parts of Egypt due to the higher humidity. Serious losses occur as a result of infection by the fungus. Dense canopies resulting from high fertility of seedless grapes or from using higher levels of GA3 agrivate the situation . With the objectives of enhancing berry colouring, reducing bunch rot and eliminating fungicides application, the following work was carried out.
Materials and methods
This trial was conducted on 7-years old Flame seedless grapevines. The vines were vigorous , double cordon trained, spur pruned and planted at 2x3 m. The treatments were : 1)- Leaf removal at cluster-set by removing leaves from above, opposite and below the cluster. 2)- Spraying the clusters with iprodione (Rovral) 50 w at 2 pounds / acre either at bloom, pea-size or verasion . 3)- Integrated leaf removal and fungicide application, and 4)- A non sprayed control. At harvest, bunch rot incidence was evaluated by counting diseased bunches per vine. Severity rating was based on the percent of rotted berries 1 bunch.
Results and conclusion
Botrytis bunch rot was relatively low in incidence and severity as a result of leaf removal and one fungicide application. The differences between the treatments were significant. Bunch rot was reduced from 9.8 % in the control to 2.0 % in the leaf removal treatment. Disease severity as percentage rot by weight was also reduced by leaf removal and fungicides. Bunches on the control vines had an average of 2.4 % rot compared to 0.4 % on vines with leaves removed. A single fungicide application at bloom; or pre-close did not further reduce disease incidence in the leaf removal vines. Fungicides gave slightly better disease control when applied at bloom or pre-close .
In conclusion, Fungicides alone, did not provide adequate protection against <1> Botrytis cinerea during severe disease pressure. They became less effective as the grape mature because of heavy canopy growth anbd bunch compatness. It is evident that controlling bunch rot of grapes by leaf removal could be a practical alternative to repeated fungicides application.
1. Hegazy AH, Abdel-Kawi AA. 1992. Proceedings Hyderabad- India, Viticulture Conference, pp. 239-246.
2. Larry JB, Gubler WD, Marios JJ, Bledso AM. 1989. California Agriculture, 43, 9-11.