Evaluation And Development Of Fungicides On Apple Canker

Apple tree is the main fruit tree that cultivated in our country, with the improving of the cultivation techniques, the yield of the apple occupy the first place in the world in nowadays. Valsa apple canker is one of the most serious disease for apple in China. Currently people use so many different chemicals to control the disease. Because the effects of these chemical are quite different, it is urgent to make tests and evaluate the functions of these chemicals. Bio-control of plant disease is getting more and more attention. In this paper, a natural product from Chinese herbs was developed and its inhibitive effects against Valsa canker disease was also tested.Based on the currently used fungicides on Valsa apple canker, 19 fungicides were tested and evaluated. The results showed that 9 kinds of chemical fungicides gave better inhibitory effects against the pathogen. They were 40% Flusilazole EC, 75% Tridemorph EC,25% Difenoconazole ME,45% Propiconazole ME, 50% Kresoxim WDG, 50% Iprodione SPX, 6.5% Dioctyl divinyltriamino glycine AS, 45% Ambam 3.3% thiophanate-methyl EW respectively. The 25% Difenoconazole ME had the lowest EC50. A field experiment was carried out using these 9 kinds of fungicides with scraping-cutting method, girdling method and modified scraping method on the basis of the laboratory bioassay. The results showed that: in the method of scraping-cutting, 6.5% Dioctyl divinyltriamino glycine AS had a better effect, the disease spots expanding rate was 0 with a concentration of 650μg·mL-1, while it was 1300μg·mL-1 in the method of girdling method. 50% Iprodione SPX had a perfect effect when it came to the modified scraping method, the issue had a more Callus induction and the disease spots did not expand with a concentration of 10000μg·mL-1. In general: 6.5% Dioctyl divinyltriamino glycine AS had a better effect in the field experiment. To achieve a perfect effect, different fungicides must combine with different methods.Alcohol extracts of 40 kinds of Chinese medicinal herbs were obtained. First, growth rate method was used to screen antimicrobial activity of the herbal extracts, the better ones were used in the detacthed branches testing with the girdling method. With the primary and secondly screening, Coptis chinensis, Lily magnolia, Magnolia officinalis, Cnidium, Pulsatilla chinensis, Sophora flavescens, Piper longum with good inhibitory effect by crude extracts at 2000 times were selected, Pulsatilla chinensis crude extracts had a perfect effect not only in bacteriostatic action but also in the field experiment to control the expanding of the disease. After formulated with different additives, based on the evaluating of thermal storage stability, cold storage stability and film-forming ability, a natural product FF was developed. Bioassay tests showed that FF had the best effect in bacteriostasis with a inhibitory rate of 22%. Further tests showed that disease spots did not expand in detached branches and in the field tests, with the same result of the 1.5% benziothiazolinone EW.