Bio-Control Bacteria And High-Efficiency Low-Toxicity Fungicides Lab Screening Of Pear Canker

Pear production in China accounts for about2/3of the world and the exports accounts for about1/6.As the largest pear-producing country, China plays a pivotal role in the development of pear. However, pear canker comes on so much every year in the major pear-producing areas in China that it leads to lower production, trees’ death, and even more the gardens’ destruction. So the disease has brought a great threat to pear industry in our country.This article has made some progress on chemical and bio-control bacteria lab screening for pear canker:1. Comparing the different methods of vaccination, the author has found a basic inoculation method to pear canker.2. Detected PG activity in fermentation broth, and results showed that V.ambiens could also secrete PG,as an infectious agent of pathogenic fungi.In addition, the PG activity changed with the fungus growing in mediem.Otherwise, after inoculated about5days, the enzyme is in its highest activity.3. Strain CL-9was isolated and purified from soil samples in pear tree’s rhizosphere in Changli in Hebei Provence. The stain has obvious inhibition effect on Valsa ambiens(Pers.)(inhibition zone AR=12mm). It’s identified as Paenibacillus polymyxa. It can produce two kinds of hydrolases, proteinase and glucanase, but no chitinase or glucanase. And it’s indicated by antagonistic tests that the fermentation filtrate could produce some kind of active compounds which can significantly inhibit the growth of V. ambiens. After handled by filtrate and heated filtrate, the hypha changed into tighter, tubbier, and less branches. Meanwhile, stain CL-9has a wide range of antagonistic spectrum which shows obvious inhibition to15pathogens of common fungal diseases on crops and horticulture plants. The radius of inhibition zones changes from5mm to17mm. The strain has higher antipathogenic activities and a wide antagonist spectrum that could supply a technological foundation for developing bioagent. As an addition to chemicals, it will turn down the chemical pollution. 4. Strain CL-9has been proved that it has much bio-control effect on pear canker in indoor simulation tests, whether by lowing incidence or reducing length of scab.5. This article screened5kinds of higher efficiency, lower toxicity fungicides (EC50<50) from20common kinds, in chemical screening experiments.