Diagrammatic scale for measuring severity of gray mould in thornless Castilla blackberry (Rubus glaucus Benth)

ABSTRACT: Gray mould, caused by the fungus Botrytis cinerea Pers., is a disease that largely affects the crops of Rubus glaucus Benth. (Castilla blackberry) in Colombia. In spite of the economic losses that it causes in the production of Castilla blackberry at national level, a standardized method to quantify the disease severity caused by this fungus in the fruits has not yet been reported. In the present work, a diagrammatic scale was prepared to assess gray mould severity in thornless fruits of R. glaucus. The proposed scale showed the levels of 5, 10, 20, 40, 60, 80, and 100%. Photographic images were obtained for each of these levels, which were processed using the ImageJ software. The scale was validated by 13 evaluators who assessed affected fruits with and without the scale. The precision and accuracy of each evaluator was determined by simple linear regression between actual and estimated severity. The evaluators showed better precision, accuracy, and reproducibility in the assessments performed with the scale. The proposed scale is appropriate to estimate the severity of gray mould in R. glaucus fruits.

New fungicide for narrow-leafed lupin protection

Diseases are one of the main factors decreasing narrow-leafed lupin productivity. Anthracnose is the most harmful among the lupin diseases set. Complex fungicides with high protect and curative action against this disease and without negative action for protected crop plant should be used. High effectiveness of the fungicide Bamper Super (prochloraze, 400 g/l + propiconazole, 90 g/l) against anthracnose pathogen at the dose 1.5 l/ha has been revealed under laboratory conditions. During tests years effectiveness of this dose against this disease was 91% under the field conditions. The tested fungicide has high protection ability against Fusarium, botrytis gray mould and sclerotinia. It was specified that double narrow-leafed lupin crops treatment by the fungicide Bamper Super decreases diseases spreading and harmfulness under favorable for disease development conditions and prevents significant losses of seed yield. Because of use of this fungicide saved seed yield of narrow-leafed lupin made 0.8 t/ha during the tests years (2016–2018). In this case, the cost recovery was 2.1 rubles per each invested ruble.