Report on Tests of Aluminum Phosphide Fumigation through Different Application and Recirculation Methods

摘要

In order to control the resistance of stored grain pests to PH3 in the high temperature and high humidity areas of our country, improve the pest killing effect of recirculation fumigation and reduce the cost of control, Wuzhou Grain Depot, State Grain Reserves has performed the tests of recirculation fumigation in the whole warehouse and recirculation fumigation under sheet through the application of aluminum phosphide on the surface of grain mass and the application of aluminum phosphide in the vent of ventilation duct for many times since 2000, these tests were performed in three horizontal warehouses separately of which lengths were 51.2m, the widths were 20.5m,the eaves height were 7.8m,and there were eight fumigation tests performed with different application dosages,different application ways, different airtightness, different recirculation ways early or late. This article reports summary and analysis according to the results of these tests;test results showed that when airtightness of the warehouse was not changed, holding time of the PH3 concentration and unit dosage showed a positive correlation, i. e. the less unit dosage, the shorter holding time of certain concentration. Fumigation efficacy was not good when PH3 fumigation time was less than 28 clays;the recirculation fumigation through intermittent application had certain advantage under the same airtightness condition compared with recirculation fumigation through single application, and the control effect of the former was better obviously; the airtightness halflife time of the No. 6 warehouse was increased from 60s to 98s and the unit dosage of the fumigation was reduced from 6g to 5g;for the recirculation fumigation through single application, the holding times of the concentrations above 300 mL/m3 and 200mL/m3 were prolonged obviously and reached 21 days and 40 days, respectively. No live pest was found two months after the fumigation, the interval between two fumigations was prolonged to more than 257 clays and obtained better effect of control; performed the test of the recirculation fumigation through intermittent application which combined application on the surface of grain with the secondary application in door of ventilation duct on the floor in the No. 10 warehouse,holding times of the concentration above 300 mL/m3 and 200mL/m3 were 38 day and 48 days, respectively. The interval between two fumigations was prolonged to 317 days,the fumigation effect was better than that of the No. 6 warehouse;for the recirculation fumigation under film in the No. 18 warehouse, the airtightness (300Pa) halflife time was 135s,when we used intermittent application by combination with the secondary application in vent of ventilation duct, the holding time of the concentration could be longer and the fumigation effect would be better;therefore, this method has useful value in management of the resistance of stored grain pests to PH3. This article also presented the requirement for the operation of recirculation fumigation through application in vent to ensure safety and effectiveness.