The Effect of Chitinase on Didymella applanata, the Causal Agent of Raspberry Cane Spur light

In vitro and in vivo studies were conducted to assess the efficacy of the two microbial chitinases Chi I (from Streptomyces sp.) and Chi II (from Serratia marcescens) on Didymella applanata (Niessl.) Sacc., the fungus which causes spur blight of raspberry (Rubus idaeus L.). D. applanata was isolated from canes of diseased raspberries in a plantation in Novosibirsk, Russia. In vitro, the effective concentration of Chi I that reduced the growth of D. applanata was 0.4 U/ml (p = 0.05), but Chi II had no influence on the growth of the fungus in medium. In inoculation experiments on raspberry canes, both chitinases at the rate 0.5 U/ml reduced fungal development. In plantation where canes were inoculated after spraying with chitinase, fruiting bodies of fungus failed to form in all enzyme treatments, whereas a significant number of these fungal fruiting bodies (12.8 per cm²) developed in control treatments lacking chitinases spraying. The chitinases reduced the size of lesions and limited the infection of internal tissues of canes. Field testing of Chi I under natural conditions showed a significant suppression of the independent spur blight. These studies form the basis for further evaluation of ecologically benign control measures for raspberry spur blight.     

Evaluation of the effects of biological preparations on phytopathogenic fungi Didymella applanata and Botrytis cinerea

Fungicidal and fungistatic effects of biological preparations involving bacteria of the genera Pseudomonas and Bacillus and fungi of the genus Chaetomium on phytopathogenic fungi Didymella applanata and Botrytis cinerea were evalauated. All the biological preparations under study inhibited the growth of colonies of the fungi; however, the degree of the inhibition depended on the nature of each particular microorganism and the concentration of each particular preparation. The preparation containing Bacillus subtilis at a concentration of 0.2% effected maximum suppression of B. cinerea (the diameter of the colonies decreased sevenfold). The preparations containing bacteria of the genus Pseudomonas and fungi of the genus Chaetomium were most efficient in suppressing D. applanata. The preparations containing B. subtilis and Chaetomium spp. showed promise as agents against simultaneous development of spur blight and Botrytis blight.     

Evaluation of the Effects of Biological Preparations on Phytopathogenic Fungi Didymella applanata and Botrytis cinerea

Fungicidal and fungistatic effects of biological preparations involving bacteria of the genera Pseudomonas and Bacillusand fungi of the genusChaetomium on phytopathogenic fungi Didymella applanata and Botrytis cinereawere evaluated. All the biological preparations under study inhibited the growth of colonies of the fungi; however, the degree of the inhibition depended on the nature of each particular microorganism and the concentration of each particular preparation. A preparation containing Bacillus subtilis at a concentration of 0.2% effected maximum suppression ofB. cinerea (the diameter of the colonies decreased sevenfold). Preparations containing bacteria of the genus Pseudomonas and fungi of the genus Chaetomium were most efficient in suppressing D. applanata.Preparations containingB. subtilis and Chaetomium spp. showed promise as agents against simultaneous development of spur blight and Botrytis blight.     

Field testing of BACTICIDE®, PHYTOVERM® and CHITINASE for control of the raspberry midge blight in Siberia

Three products based on compounds of biological origin were tested for their ability tocontrol the raspberry midge blight in theSiberian region of Russia. Bacillusthuringiensis subsp. israelensis(BACTICIDE^®) and Streptomycesavermitilis metabolites (PHYTOVERM^®) were used against Thomasiniana theobaldi (ageneral member of the midge blight) andCHITINASE was used against fungi (mainly Didymella applanata) associated with T. theobaldi. The BACTICIDE^®(0.2%) and PHYTOVERM^® (0.2%) sprays caused a 2-fold decrease in midge blight severity and the sameeffect was obtained with chemical insecticides.The CHITINASE (1%) spray caused a 4-folddecrease in the severity of midge blight. Inaddition, CHITINASE and PHYTOVERM^®caused a significant suppression of theindependent spur blight. These studies form thebasis for further evaluation of ecologicallysafe control of the raspberry midge blight.