INSECT PESTS ON CARROTS

Press, Volume LXXXIX, Issue 27047, 23 May 1953, Page 6

INSECT PESTS ON CARROTS

SUSCEPTIBILITY OF VARIETIES RESULTS OF SCIENTIFIC TRIALS Two major insect pests of carrots in New Zealand are the carrot aphid and the carrot rust fly. The carrot aphid frequently causes the tops of carrots and parsnips to wilt, and when the attack is severe, plants may be killed. -Carrot rust fly larvae feed on the roots and produce stunting, dwarfing, or complete destruction of plants, especially when plants are attacked at an early stage of growth. Three field trials involving six carrot varieties have been made at Auckland and Palmerston North by Mr K. P. Lamb, of the Plant Diseases Division of the Department of Scientific and Industrial Research, to compare the aphid susceptibility of the various carrots. Observations were also made of yield and the incidence of carrot rust fly. Results of the trials, published in the latest issue of the “New Zealand Journal of Science and Technology,” show that the Osborn Park variety was the highest yielding, and showed least damage from aphid attack. It was, however the most heavily infested with carrot rust fly. Manchester Table variety was least infested with rust fly, but supported the most dense aphid populations, and was the most damaged by aphids. Chantenay, Early Horn, and James Intermediate were moderately damaged by aphid attack, and at maturity were moderately infested with rust fly. The Holmes Improved variety was more vigorous and higher yielding than the previous group, but lower yielding than Osborn Park. Mr Lamb says that for high yield and vigour, Osborn Park emerged as an outstanding variety in these trials. It was followed by Holmes Improved. The group comprising Chantenay, Early Horn, and James Intermediate was more or less homogeneous in most respects. Manchester Table was the lowest yielding variety in the Auckland trials. All varieties were suitable for table use.

Osborn Park and possibly Holmes Improved varieties would be better suited for areas where carrot aphis is a serious problem, but carrot rust fly is not, according to Mr Lamb. Manchester Table variety would appear to be less suited for such areas.