Study On The Hebei Pyrus Bretschneideri Black Spot Disease (Alternaria Alternata) Quarantine Treatment

USA proclaimed that the import of Hebei ya pear were discontinue results from the new microspecies were been detected on ya pear in 2002. In order to open the USA market, it is necessary to find quarantine treatment technology of A. alternate.We studied on the completely killing condition of hebei ya pear's A. alternata (Fr.) keissle with indoor virulence test. The results showed that A.alternata could be fully killed in 60℃water dipping 10min. Effection of fungus inhibition ratio in 55℃hot water treatment group was the largest with dipping 10 min, meanwhile the 60min treatment group in the same dipping temperature got the same reulsts too. Treating fungus in 750mg/L prochloraz solution 30min at 30℃was able to kill A.alternata, and the inhibition ratio markly raised most in 450mg/L10min or 300mg/L 30min at prochloraz treating. Using prochloraz treating fungi at 40℃the inhibition ratio was significant better than at 30℃with same other treatment condition. The fungus was able to be completely killed in 200mg/L imazalil solution 40min and 300mg/L imazalil solution 20min. The inhibition ratio increased fastest at 20min with the same concentration and in 300mg/L imazalil soulition 20 min. Treating fungus 20min, the effect of 40℃was the best otherwise 30℃was the worst, and 300mg/L imazalil solution could fully killed it. The effect of thiabendazole and captin were very bad.Specification of hot water treating ya pear was studied also. Although each treatment methods significantly effected ya pear's losing weight, it is still in the quarantine treatment acceptable range. The specification that preheating time was 12h, pretemperature was 25℃or 30℃, treatment temperature was 40℃, treatment time was 10min or 20 min, and after treatment pear was decreased in room temperature then storaged in cool condition was determined. All the pear's temperature changing methods were paripassu. Fruit surface temperature risded fast at beginning few minutes then tend to steady gradually and centrum temperature went up slowly all the time. At cooling period, pear surface temperature decreased quickly, on contrary, centrum temperature increased in few minutes then turned to cooling. The effect on temperature changing of treatment fruit were similar at 10min and 20min treatment. Curvilinear equation of temperature changing with time changing was logarithmic curve or quadric-curve or thrice-curve. The filate relation was significant.Ya pear's quality was detected after hot water and fungicide treatment. The changing of saccharide content and acid content and fruit firmness were fairly small in all the treatment methods. Although all the treating group's losing weight ratio were higher than non-treating group's, the ratio can be acceptable in quarantine treatment. The surface of ya pear browning in higher concentration than 150mg/L prochlaraz, and The 25℃preheating group was better than in 30℃. As far as drug induced sufferings was concerned, treating in 35℃, preheating pear in 25℃group was able to suffer dipping in 150mg/L prochlaraz within 20min and dipping in just 50mg/L imazalil within 20min then storaged in 4℃, and preheating in 30℃group can acceptable treating in 75mg/L prochlaraz 20min and treating in 50mg/L imazalil within 10min then storaged in room temperature yet treating 20min only can be stored in 4℃. Treating in 40℃, ya pear can suffer the highest condition was soaking in 150mg/L prochlaraz 10min and 100mg/L 10min then storaged in 4℃, and soaking in 300mg/L prochlaraz 10min and 50mg/L imazalil 10min then stored in room temperature, moreover the preheating temperature may be 25℃or 30℃in the two stored way.Ya pear was fine dipping in 200mg/L prochlaraz 20min with 35℃or 40℃after treated by combination way, nevertheless the surface became drug induced sufferings in low imazalil concentration. Fungicide liquor mixed with Vc may decreased drug induced sufferings rate and browning rate not as imazalil, on the other hands the effects isn't obvious when mixed with CaCl₂. Choseing method can't inhibit pathogen's growth finally. It is needs to do more experiments on this part.