Transmission of cushion gall of cacao by means of tissue transplantation

1. Experimental transmission of greenpoint gall and flowery gall of cacao was attempted by means of tissue transplantations from typical galls to the stalks of cacao pods in gall-free trees. The inoculations were performed in July and August, 1959. Out of 143 inoculations using greenpoint gall tissue, 14 of the inoculations, or 9.7 percent, developed greenpoint galls on the pods stalk. The incubation period varied from 34 to 57 days for 8 of the inoculations, and at longer intervals up to 111 days for 6 of the inoculations. 2. Flowery gall inoculations by tissue transplantation into pod stalks of normal trees have yielded no positive results as yet. 3. In 102 check tests, in which tissues from normal flower cushions in gall-free trees were applied to pod stalks of normal trees, there was no indication of gall formation after 98 days. 4. Now that positive transmission of greenpoint gall appears to have been demonstrated in 14 cases, it is hoped that refinements in the technique may throw considerable light on some of the questions concerning cushion gall, and may advance the usefulness and application of tests methods.