Cereal-Grass And Grain Aphides

Press, Volume CVIII, Issue 31760, 17 August 1968, Page 10

Cereal-Grass And Grain Aphides

TAURING June and July the Plant Diseases Division of the Department of Scientific and Industrial Research surveyed a number of cereal crops from Blenheim to Invercargill for the presence of the cereal-grass aphis (Rhopalosiphum padi) and for the grain aphis (Macrosiphum mascanthi).

In Canterbury greenfeed oat crops were quite severely infested with the cereal-grass aphis. In the 18 crops examined, 11 had 80 per cent or more of the clump samples infested with aphides, and the over-all average was 10 samples infested out of the 15 examined in each crop.

The cereal-grass aphis was present in the five barley greenfeed crops examined, but in lower numbers than in the greenfeed oats. The average was six samples infested out of the total of 15 examined in each of the five crops. Volunteer wheat or barley plants were examined on 16 occasions. The cereal-grass aphis was present in all but one of these crops and the over-all average was seven samples infested out of the 15 examined in each crop. The grain aphis was found in seven greenfeed oat crops and four wheat crops. The greenfeed oat crops were located at Waikari, Scargill, Omihi, Darfield, Hororata, Waimate and Oamaru. Three of the wheat crops were early

sown (either April or early May) and were located at Blenheim, Masons Flat and Taieri, while the other crop was volunteer wheat at Hororata.