Occurrence Regularity Rust, Biological Characteristics Of Leaf Mold Pathogen And Chemical Control Of Prickly-ash

Zanthoxylum bungeanum Maxim. is shrub or dungarunga, originating from China andbelonging to Zanthoxylum, rutaceae. It is one of the most economically important tree species.In recent years, Prickly-ash disease has become rampant due to the large scale of plantationand changing weather conditions. It is reported that diseases and pests on prickly-ash havedecreased yield by half, two of which are prickly-ash rust disease and leaf mold. Therefore, inorder to guarantee yield, quality and quantity of prickly-ash, people should first understandthe occurrence regularity, temporal dynamics and chemical control methods of prickly-ashrust. This research was done on occurrence regularity, temporal dynamics, chemical controlexperiments in the field, biological characteristics of prickly-ash leaf mold pathogen andfungicide selection indoors. The main conclusions were as follows:1. Field investigation of prickly-ash rust disease in Shilidian, Feng county, Shannxiprovince showed that prickly-ash rust has onset in late mid-July into August Pfeiffer period,the maximum value of prickly-ash rust disease rate0.888; onset peaked in mid-September, themaximum disease index74.5; late September to early October, crown disease index decreasedsignificantly, the rust popular temporal dynamics analysis showed rust occurred in line withGompertz growth model. Prickly-ash rust prevalence is closely related to meteorologicalfactors, late summer early autumn high humidity,18~22℃temperature conducive to rustepidemic.2. It was shown that Da-hong-Pao prickly-ash of Feng county displayed two differentoccurrence rate and disease index in two different site conditions. That is, occurrence rate anddisease index in He-gou-di was bigger than that in Ban-shan-po. This was also a directevidence that prickly-ash rust disease was related to microclimate.3. Chemical control experiment in the field showed that15%triadimefon and43%tebuconazole were more significant in controlling rust disease than control, with the averagecontrol efficiency being78.9and76.82.4. It has been observed in diseased leaves prickly-ash leaf mold to form the frontchlorotic, irregular brown spots, gray and black mold spots on the back layer, can also befound on the petiole when serious mold layer, diseased leaves off a lot of yellow. Through the microscope, prickly-ash leaf mold of diseased leaves was identified as false prickly-ashCercospora Pseudocercospora zanthoxyli (Cooke) Guo&Lui. The results show that thebiological characteristics were measured:prickly-ash leaf mold pathogen growth medium toPPDA optimal growth conditions, followed by the PDA medium, mannose best carbon andnitrogen sources peptone as appropriate; The optimum growth temperature is25℃and pHvalue of its pathogen falls5~6good growth conditions; little effect on colony growth of itsillumination.5. Fungicide selection experiments indoors showed that in6tested fungicides,tebuconazole had the best fungicide effect on prickly-ash leaf mold (EC50=0.0471), followedby mancozeb and mildothane (EC50=3.064and4.414) and the least fungicide effect was foundby polyoxins (EC50=58.103).