CAB129-37 — Page 408

showed that 70-100 per cent. of the stems were infested. Eventually the infesta-- tion reached 100 per cent. in nearly all varieties. Very few heads were killed. in spite of the heavy borer attack and the varieties would have yielded well were it not for Calidea damage. The outstanding exceptions were the two plots of Feterita Managil and Martin's Milo sown on 9th March. These had 50 per cent, and 20 per cent. infested stems respectively, but the caterpillars found were so small that damage was neglible,

The heads of sorghums which did not emerge completely from the boot were often severely damaged by caterpillars of the stem-borer and other moths. The heads of varieties which have the grain tightly packed were damaged by cater- pillars of a small moth, Eublemma gayneri, but those of varieties with more open heads were not attacked, perhaps on account of the different environment conditions in these heads.

Stem-borer infestations of 100 per cent. were recorded on several native farms,. but blue bugs were not seen.

(d) Maize. The several varieties grown were only lightly infested by borers. (e) Castor oil. Caterpillars caused serious damage to this crop, completely defoliating the early-sown plants. Leaves, inflorescences and developing pods. were all attacked.

(f) Sesame. Flea beetles seriously damaged the seedlings and caterpillars. severely damaged the remaining plants when they were setting seed.

(g) Safflower. No appreciable damage occurred, although some plots carried a fairly high population of Aphides.

(h) Cotton. Cotton-stainers appeared in numbers when the bolls had set and some staining occurred.

(i) Niger oil. This crop was not damaged by insects during the growth period, but numbers of weevils were found in the ripened heads.

(j) Soya bean. This crop was remarkably free from insect attack.

(k) Lupins. The plots on Units 1 and 2 were defoliated completely by cater- pillars when they reached the flowering stage.

(1) Sweet potatoes.

The six varieties under trial were completely defoliated by hawk-moth caterpillars from the windrows. Several instances were observed. of the caterpillars adopting a diet of sunflower leaves and completing growth.

(m) Various legumes. Cowpeas on the experimental plots were severely damaged by various caterpillars and brown stink-bugs at the flowering and early pod stages. About 90 per cent. of the pods were totally or severely damaged. An earlier commercial sowing produced a fair crop, but damage was done by the above insects and a leaf-eating beetle and its larvæ in addition. Fiwi beans. were also damaged by caterpillars and brown stink-bugs. The yield of chick- peas was reduced somewhat by caterpillars which fed on the developing seeds.. Pigeon-pea and sunnhemp were not damaged.

Southern Province

On the 25 variety

(a) Groundnuts. Rosette disease was generally present. trial the infection was estimated to be 1.000 plants per acre. Aphide infestation was definite but slight. On native plantings in the Masasi area, the number of rosetted plants varied between 250-3,250 per acre.

(b) Sunflowers. At least eight species of plant bugs were feeding on this crop, and of these, three were breeding. No damage could be attributed to them.

(c) Sorghums. Damage by stem-borers was not so great as in the Central Province, and no blue bugs were seen. Central shoot-fly caused a considerable reduction in stand.

(d) Maize. No stem-borers were present.

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