Impact of nozzle jet angle on the efficacy of plant protection products applied for control of pests and diseases of apple | Vpliv kota curka sob na bioticno ucinkovitost pripravkov za zatiranje bolezni in skodljivcev jablane

In a plantation of apple trees trained in the super-spindle form, in 2004 and 2005 field trials were conducted to examine the impact of nozzle jet angles on the biological efficacy of plant protection products for control of pests (green apple aphid - Aphis pomi and codling moth - Cydia pomonella) and diseases of apple (scab - Venturia inaequalis and powdery mildew - Podosphaera leucotricha). Different nozzles types (Albuz AVI, ATR and Lechler ID, ITR TR) with different jet angles (80, 90, 110, 120) were used for application of all the preparations throughout the whole season, in equal doses and with equal spray volume used per hectare (i. e. 350 l/ha). The same spray programme was applied with different types of nozzles. Standard randomised block design in four replications was used. The plots were five rows wide (5 x 2.8 m) and 30 m long (approx. 400 m2 each). Assessments of disease severity and pest attack rate were conducted in six crown positions; two in the bottom, two in the middle and two at the top of the tree crown. On average, on all of the six positions assessed on the trees, the nozzles with wider spray jet angles (110-120o) gave slightly better or comparable disease control results than nozzles with narrower jets (80-90). With regard to the efficacy of insecticides applied for control of aphids and codling moth, the differences between wide- and narrow-angle nozzles were even smaller than in case of fungicides. At comparisons of results at tree tops (position top-inside and top-outside) we established that biological performance of fungicides and insecticides applied with wide-angle drift-reducing nozzles (AVI and ID) was better than when applied with narrow-angle nozzles with hollow cone jets (ATR and TR). According to the results of trials it could be concluded that, when applying fungicides and insecticides to apple tress trained in a super spindle form, the wide-angle flat fan nozzles (AVI and ID) will provide equal biological performance of preparations to the narrow-angle hollow cone nozzles (ATR and TR).