Effects of Beauveria bassiana on Disease Biocontrol and Growth of Ornamental Sunflower

Ornamental sunflower (Helianthus annuus L.) is an important horticultural plant supporting China’s cut-flower industry. But its cultivation is often affected by root-, stem-, leaf- and disc-rot diseases causing a drastic reduction in the commercial production of this flower. So far, using improved variety and pesticides could not bring much success to this problem. In the present investigation the prevention of the diseases has been tested using a biocontrol fungus species Beauveria bassiana Bals. -Criv. In the present experiment, B. bassiana and ornamental sunflower were colonized into ornamental sunflower cultivation beds, and then the sunflower was infected with nuclear disc bacteria. The intensity of the disease resistance effect by B. bassiana on the morphological characteristics of ornamental sunflower plants was monitored. Experimental data show that both seed immersion treatment and root filling treatment can improve the resistance effect of ornamental sunflower to nuclear disc bacteria. The disease resistance effect of seed immersion treatment is more obvious, which is specifically reflected in the incidence of ornamental sunflower plants. The incidence of 3, 4, 5, and 11 d were 7, 13, 6, and 30%, respectively. And the ornamental sunflower plants treated with B. bassiana showed a growth and budding effect. The budding rate of plants treated with B. bassiana seeded at 2, 3, and 4 d were increased by 36, 50, and 33%, respectively.