FIGHTING WOOLLY APHIS

Otaki Mail, 13 June 1923, Page 4

FIGHTING WOOLLY APHIS

NATURAL ENEMY AT WORK. GOOD RESULTS IN NELSON ORCHARDS. The appended letters from Nelson orehuidists show conclusively that aphelinus mali, introduced by the Cawthron Institute to combat woolly aphis, is doing valuable work. Mr. H. E. Stephens, of Stoke, writes: "I was much interested in your account of the success of the aphelinus mali seut; by the Cawthron Institute to j Auckland last year t o combat woolly I aphis, but have seen no mention of I similar results here. Last December •I was supplied by Mr. Rhilpott with a j number of tliese parasites winch 1 i liberated on a Munro tree that was I well infected with aphis. Unfortunately a heavy thunderstorm occurred within an hour of their liberation, ami as the wire netting round the tree was not covered with scrim, I thought 1 hud lost the lot. 1 watched the tree carefully for months without seeing any result until just recently, when on examining the nee I found that some of the twigs were covered with the black skeletons of woolly aphis, each with a hole in it, showing that the aphelinus was at work. 1 also found adult aphelinus on the tree. I am hopeful that next spring will see such an increase in these parasites that woolly aphis will soon be a thing of the past in Nelson orchards: and as a fruitgrower I wish

i to voice our appreciation of the good ' work that is being done for us by Dr. Tillyard and the Cawthron Institute." Mr. H. Pickup, Stoke, writes: "A little over a year ago, Dr. Tillyard asked me to select the apple tree most affected with woolly aphis and surround it with 1-iueh mesh wire netting, to keep out birds. I happened to have a tree that had been knocked about a bit (;t Munro), and il was white with the blight. This 1 netted in as instructed Sand Mr. Philpott came along and liberSated about SO aphelinus mali. Shortly t after Mr. Philpott came again and saw I that numerous aphis were parisitised. j II was asked not to spray the tree and j did not do so during the following win-

ter and spring, nevertheless the woolly aphis gradually died out and all through this summer the tree has been, and is now, quite clean and free from blight. Again early this season, I received a large consignment of aphelinus mali Or. Tillyard and liberated them on other badly infested Rokewood trees. I soon* 1 saw they had got right down to business on the woolly aphis, and, I feel confident, the effect will be as. good as in the first, experiment." Mr. R. H. Simpson, of Stewart Block, near Redwood's Valley, writes:—"ln January last we received from the Cawthron institute a number of tubes of j aphelinus, and liberated the insects on different trees in the orchard affected by woolly aphis. On recent examination

of the trees, the work of thes little insects is plainly discernible in all parts of the orchard. On the trees on which I the aphelinus were liberated, thousands Of dead aphis shells are to be seen, and bunches of woolly aphis have been clenaed right up. On warm days great , numbers of the little insects can be I seen crawling up the branches. The J trees have been sprayed twice with lime sulphur and arsenate of lead since the insects were placed on them, but it apparently has done them no harm. If this little insect once get-, properly established in the orchards, the eradication of the woolly aphis pest is cer- , tain." j Mr. L. Mackay, of the Moutere, has ■ informed Dr. Tillyard that he has found j the aphelinus doing good work, and j that it is spreading in his orchard. (