Studies on Longan W itchesp Broom Disease

he results of longan seedlings with witches'broom disease immersed in tlie solutions of tetracycline-HCl(500,1500ppm for four hrs)and penicillin-GK(5000 ppm for four hrs)showed that thesymptom of the diseased seedlings were unable to be inhibited,which indicated that the disease was notcaused by MLO and BLO.The bunchy filan1entous viruses were found in the sieve cells of the diseasedleaf under electron micrcacope,no virus particle were deteeted in healthy plant used as control.Thevirus particle simil lar to that existed in the diseased leaves can be trapped from the salivary glands of Tessaratoma papillosa Drury(adults)and Cornegenapsylla sinica Yang et Li(adults)by SPA-ISEMmethod.It is concluded that the virus particles are the causal agent of Iongan wi tches'broom disease.