金丝小枣浆烂果病症状、危害及病原菌鉴定

金丝小枣浆烂果病严重危害我国北方枣树 ,并且逐年加重。本研究通过室内分离培养与田间调查 ,经多年多地试验 ,查明此病的症状、危害及病原菌。结果显示 :金丝小枣浆烂果病在河北、山东、天津的产区普遍发生 ,以河北泊头市发病最重。该病在枣果进入白熟期 ( 8月 2 0日左右 )开始发病 ,形成侵染点明显的红色近圆形软腐病斑。 1998— 2 0 0 0年 3年平均发病率和病情指数分别为 36 7%和 2 6 9。依据柯赫氏法则对金丝小枣浆烂果病病原菌进行了研究 ,根据病原菌形态特征 ,病原菌有性阶段鉴定为囊孢壳菌 (Physalosporaobtuse(Schw .) ) ,无性世代鉴定为梭壳孢菌 (Fusicoccumsp .)。经黑光灯诱导后 ,囊孢壳菌在室内PDA培养基上可形成子座与分生孢子器 ,有性世代的子囊壳与子囊孢子只发现于越冬后的病枣果中。

Preliminary Identification of Loquat Leaf Mould Pathogenic Fungus in Mengzi City of Yunnan Province

[Objective] The study aimed to investigate the Ioquat leaf mould disease in Mengzi City of Yunnan Province and lay the foundation for determination of effective prevention and control methods.[Method] Loquat leaf mould pathogenic fungus was isolated by tissue separation method and inoculated with conidial suspension.The pathogenicity of Ioquat leaf mould pathogen was verified by Koch＇s postulate.Under a microscope,mycelial morphology and conidial fructification were observed,spore sizes were measured,and Ioquat leaf mould pathogen was identified according to the morphological characteristics.[Result] Velvet-like,olive green fungal colonies were generated on PDA medium.Conidiophores erect,apex curved,dark brown,smooth,with obvious spore marks and no diaphragm,（33.0-152.8） μm×（2.6-4.0）μm.Cladosporium was brown or pale olive with spore marks,monocelled or with one diaphragm,（7.1-19.0） μm × （1.9-5.9） μm.Conidia concatenate （2-4）,oval or spherical,with no spore mark,light olive,monocelled,smooth,（2.1-9.4） μm × （1.2-2.6） μm.[Conclusion] Loquat leaf mold disease began to occur in the germination period of spring shoots and summer shoots and became serious in the germination period of autumn shoots.Sooty mold-like layer grew on both front and back surfaces and densely covered the whole leaves,thus seriously affecting the photosynthesis of plants.The pathogen was preliminarily identified as Cladosporium eriobotryae Pass.＆ Beltrani.

Identification of Postharvest Pathogens of Amorphophallus muelleri and Indoor Screening of Fungicides

Konjac （Amorphophallus muelleri）, a genus of tuberous plants in the Araceae family, is one of high-value crops in Southwest China. This study aimed at identifying the main pathogens causing tuber rot during storage ofA. muelleri and screening the effective fungicides, so as to prolong the storage period ofA. muelleri and decrease the losses. Isolation and identification, as well as pathogenicity test and retro-inoculation experiments were made for the pathogen causing tuber rot during storage ofA. muelleri in Kunming city, Yunnan province, China. The effective fungicides for the main pathogens were also screened in the laboratory. Six fungi were identified as the pathogens causing tuber rot of A. muelleri, which were Fusarium solani （Mart,） Sacc., Fusarium oxysporum Schlecht., Botrytis cinerea Pers., Alternaria alternata （Fr.） Keissl., Rhizopus nigricans Ehrenb., Penicillium ulaiense Hsieh, Su ＆ Tzean. The main pathogens causing postharvest diseases ofA. muelleri were F. solani, F. oxysporum and B. cinerea. The isolation frequencies of them were 33.9%, 10.5% and 19.4%, respectively. After artificial inoculation, the incidence of tubers infected by F. solani, F. oxysporum and B. cinerea was 100%, 83% and 95%, respectively. The results of chemical screening showed that, in potato dextrose agar （PDA） media plate, the compounds Fludioxonil （50% WP） and Boscalid （50% WG） were the most effective in controlling the three main pathogens, and the average effect reached more than 97%. The test of fungicidal antisepsis on tubers consisted ofA. muelleri being dipped in the 9,000x diluted solution of Fludioxonil （50% WP） or in the 3,500x diluted solution of Boscalid （50% WG） for 3 min and stored at room temperature （25 ℃） for 7 d and 15 d, respectively. The fungicidal effects of Fludioxonil against F. solani, F. oxysporum and B. cinerea for 7 d and 15 d were 88.6%/83.2%, 90.1%/84.7% and 93.0%/91.5%, respectively, whereas the fungicidal effects of Boscalid were 87.0%/85.3%, 89.0%/85.6% and 89.2%/89.1%, respectively. The results may provide useful information for the control ofpostharvest diseases ofA. muelleri.

Identification of Pathogenic Germs and Antibiotics Residues in the Raw Milk and Their Effects on Human Health

Milk is a food of great value, it provides more essential nutrient than any other natural food. The presence of pathogenic bacteria and antibiotic residues in milk can cause a real danger to consumers. Effectively, the milk consumption contaminated by bacteria can have an immediate impact which means a toxi-infection. Therefore, the presence of antibiotics residues in milk can constitute an important risk at the allergic and antibiotic resistance cases on the consumer. The present study concerning the pathogens germs identification and Antibiotic residues seeking in milk and their impact on the human health, has been realized on a total number of 80 samples of raw milk resulted from direct sale channel （dairies） throughout Blida different regions localities. The Microbiological analysis has shown only three conform samples to JORA Standards. Really, milk non-conformity results to the microbiological standards consisting on total aerobic mesophilic flora total count, total coliforms, Thermotolerant coliforms E. coli, Faecal streptococcus, Staphylococcus aureus have shown the following contamination rate： 61.25%, 93.75%, 86.25%, 55%, 93.75% and 50%. Salmonella is characterized by a total absence in all analyzed milk samples. Moreover, the antibiotics residues research by Delvotest SP make plainly visible 33 positive samples. Further, two samples of the three which were judged conform to the bacteriology standards has been found contaminated by the antibiotic residues. The analyzed milk quality can be considered as a real danger to the consumption.

Isolation and Identification of Main Fungal Pathogens in Muskmelon in Open Field of Hubei Province in Summer

Fungal diseases often occur seriously in muskmelon in open field of Hubei Province in summer, especially in continuous cropping pattern, resulting in great economic losses. In this study, the pathogens of main fungal diseases in muskmelon in open field of Hubei Province were isolated, and they were identified by morphological and molecular techniques. The results showed that muskmelon fusarium wilt is a major disease in muskmelon in open field of Hubei Province in summer, and its pathogen was confirmed to be Fusarium oxysporum. In future studies, one pair of specific primers would be designed to detect different pathogenic races of Fusarium oxysporum so as to accelerate the detection and to shorten the detection time,thereby proving guidance for actual production.