APHIDES FOUND IN MANY CROPS

Press, Volume CI, Issue 29916, 1 September 1962, Page 6

APHIDES FOUND IN MANY CROPS

A survey of about 100 wheat crops in the area from Southbridge to IVaiau carried out by officers of the Department of Scientific and Industrial Research last week showed that only onethird of the crops were free of aphides. Dr. Harvey Smith, a plant pathologist of the Plant Diseases Division at Lincoln, said this week.

Severe infestation of earlysown crops was common in all districts, except between West Melton and Hororata. he saiid. The most severe infestations were beginning to show in the crops with a yellowing of the lower leaves and these had an average of two aphides a plant. “At least one crop in every five had an average of one aphis a plant and should be sprayed as soon as possible to get the maximum benefit from the control of yellow dwarf virus, which is becoming quite noticeable around

the margins of crops,” Dr. Smith said. “A noticeable feature of this survey was the rapid increase in aphides over the last few weeks and the higher number of aphides found in the margins at crops. Several crops which had been sprayed previously were examined and found to be either completely free or with very low aphis numbers. “A ohaiin strip around the headland should be sprayed if aphides are common there but not prevalent through-out the crop. Both aerial and ground application of the systemic insecticides. Rogor and Metasystox. have been found to give excellent control at the rate of application of 12 ounces an acre.” he said. Further trials are in progress to determine the lowest effective rate of application.

Dr. Smith said that it was expected to carry out a survey of areas south of the Rakaia next week.