CONTROL OF GORSE.

Timaru Herald, Volume CXXXIV, Issue 18914, 27 June 1931, Page 8

CONTROL OF GORSE.

PROBLEM OF FLOWERING. BOTANICAL RESEARCH. Botanical research into the gorse plant is at present being carried out by Dr. H. H. Allan, of the Plant Research Station at Palmerston North. Discussing the matter, he stated: ‘‘The special problem here is the period of flowering of gorse in relation to the life history of the insect (apion ulicis) by which gorse-control was to be attempted. It was found that, speaking generally, flowering began in February, reached a maximum from July to September, and ended early in December. Thus the months December, January and February showed a minimum of flowering. This flow’ering period proves a great stumbling block in the way of using apion ulicis as a controlling agent, as the insect would have to pass through the egg and larva stage during the cold months of the year. It was found, however, that in certain localities, e.g„ in parts of Taranaki and Central Otago, small areas of gorse could be found in sufficiently advanced stages of flowering at periods more suitable to apion. These areas might serve possibly as acclimatising centres. ‘‘The systematics of gorse proved to be interesting, and are being followed up. Two main types of gorse were found to be common—a dense short spined, and a more open long-spined form. These also have different, but overlapping flowering periods. Within the groups several distinct varieties occur, differing in taxonomic details, hairiness and colour of calyx, colour of corolla, and so on. Aberrant forms were also found, some of very weak habit, some with but little development of spines, some with exceedingly long spines. Some of these taxonomic features are likely to prove of importance in control work, e.g., the length of ripening period of the pods and the degree of hardiness of the pod covers. “Systematics appear to have paid very little attention to the intensive study of gorse. In Europe the species is said to exhibit no great degree of variation. In England forms resembling the two chief groups above mentioned have been noted, but no decision has been made as to their status. Certain forms noted in New Zealand suggest that they possess some u. mana blood, but the true u. mana has not yet been observed to occur. I am endeavouring to And whether any botanist abroad is making a special study of gorse. At present the indications appear to be that the botanical features shown to be true of the New Zealand forms do not lead one to view the possibilities of apion control as being very promising.'*