2003 Volume 69 Issue 2 Pages 94-101
When 1.0ml of a suspension of B. subtilis IK-1080 at 1.0×108cfu/ml was sprayed onto petals of a tomato plant at the same time as a hormone treatment to enchance fruiting, gray mold disease on petals was greatly suppressed. The number of the bacteria on the petals was 1.9×107cfu/g just after spraying and increased about 400 fold to 7.8×109cfu/g by 17 days after hormone treatment. More than 10 species of filamentous fungi, including species of Botrytis, were found on petals of tomato plants in the untreated plot, but only five were filamentous fungi and none were Botrytis, on petals of tomato plants that had been sprayed with a solution of IK-1080, indicating that this treatment resulted in a decrease in the number of species of fungi on the petals. Bumblebees, often used to pollinate tomato, were tested as a carrier for an inhibitor of gray mold, targeting tomato plant petals. We tested four types of insect vector adapter, three types that were constructed as part of the beehive and one type that could be attached to the entrance of a hive (detachable type). Many of the bees were reluctant to enter the former three types of adapter, and many pollen grains were dropped. In the case of the detachable adapter, both the number of bees leaving the hive per hour and the percentage of bees returning to the hive per hour were high (12 and 77.8%, respectively). Fruiting rates of the tomato plants visited by bees from the hive with the detachable adapter were also high (96-98%). When the detachable adapter was used, 6.0×104cfu of IK-1080 adhered to the body of each bee. The use of bumblebees as vectors to carry IK-1080 resulted in an increase in the number of the IK-1080 bacteria on the petals of tomato plants to 106∼107cfu/g at 20 days after the bees had visited the plants as well as a dramatic reduction in gray mold on petals.
