Reduction of Citrus Fruit Fungal Rot Disease using the Commercial Bio-Agent Bacillus subtilis

The results of the laboratory experiment on PDA media showed that B. subtilis at all concentrations (0.1ml, 0.5ml, 1ml/plate) led to a significant reduction in the fungal growth of the two pathogenic fungi, P. polonicum and G. candidum, with an inhibition rate that increased with increasing concentration. The effect of B. subtilis on the growth of P. polonicum was higher than that of G. candidum. In the experiment of storing fruits under natural conditions, the results showed the significant effect of B. subtilis in reducing the severity of infection in injured (artificially wounded) citrus fruits (orange, lemon, sour orange) when treated with the spore suspension of G.candidum and P. polonicum, compared to the significantly higher infection severity in the absence of the biological agent B. subtilis. The percentage of spoilage (reduction of the final fruit weight) increased in the fruits due to infection after 7 days of storage in the spore suspension treatments of G. candidum in oranges, especially in the wounded fruits compared to the normal, uninjured fruits. The same is the case with lemon and orange, as it was observed, in general, that the percentage of weight reduction in wounded fruits increased even in the control treatments than in the normal (uninjured) fruits, while the presence of bacteria B. subtilis reduced the spoilage to normal limits that did not differ from the final fruit weight in the control treatment.