THE EFFECTS OF FLOWER INDUCTION REGIMES AND DISBUDDING AGENTS ON SPRAY-FORM OF CHRYSANTHEMUM

In Chrysanthemum a rather strange aberration can be seen. Cuttings, clearly only having inactive meristems. These will develop roots and primordial leaves will grow out normally, but no new primordia are differentiated and growth soon stops. Eventually, some lower side branches may come up, but not always.

Kofranek c.s. (2,3) recognized this phenomenon to be a phyto-effect of insecticides formulated on emulsifier basis. They demonstrated that these materials may cause pinching of shoots or may prevent branching. The same phenomena can be obtained with quite different chemicals also (4, 1).

It was suggested that this activity might be used for disbudding purposes in commercial growing of Chrysanthemum. However, a satisfactory procedure never was published.

In Naaldwijk, after some preliminary screening of a large number of potentially active formulations, on a series of Chrysanthemum varieties, in a range of applications with respect to timing, dose, single or in repetition, a large experiment was set up to test a series of 'near-optimum' combinations. Some of the data of this experiment are presented and evaluated below.