The dates of implementation of protective procedures against sunflower diseases

The dates of implementation of protective procedures against the most dangerous sunflower diseases (Downy Mildew, white, grey and dry rots, alternariosis, Phiomopsis, fusariosis) are substantiated. Seeds should be treated before sowing by fungicide mixtures which are composed according to phyto-examination of seeds and results of phytosanitary monitoring of sunflower fields in previous year. Phytosanitary monitoring is done by a method of route monitoring developed in VNIIMK, seeds phyto-examination - due to Naumova’s method. Timely application of fungicides for spraying of vegetative plants is based on a dynamics of sunflower physiological resistance to diseases. This dynamics was studied on white rot (sclerotiniosis) in artificial climate chambers by inoculation of the different-aged plants with fungus Sclerotinia sclerotiniorum in favourable for its development conditions (air humidity was near 100%, temperature 22-24 °С). First spraying of the vegetative plants is recommended to do at the moment of a transformation from the highest display of the physiological resistance to its decreasing -in phase of the beginning of ray flowers flowering. In a case of an intensive disease development the second treatment should be done in 12-14 days. Dessication of sunflower sowings is done by diquat-containing preparations. In accordance to the results of our researches the following dates implementation of protective procedures can be recommended, under the absence of epiphytotic development of any disease: seed treatment before sowing, plants spraying by fungicides in phase of the beginning of ray flowers flowering and, if necessary, in 12-14 days after that, dessication by diquat-containing preparations at sunflower physiological maturity (seed humidity 30.0-35.0%), and in case of a significant development of rots dessication will be effective at seeds humidity 40.0%.