Transactions of RHASS Volume 1940 - Page 054
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| Year | 1940 |
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96 INSECT AND OTHER Pns'rs on 1939. shown that thorough consolidation of the land reduces the risks of pest attack on the crop by providing a deep, firm seed-bed which encourages vigorous growth and tillcring of cereals. ltolling and cultivation of the young crop will later serve the same end and enable it to become Well established before wireworm attack begins. Not only does the proper preparation and cultivation of the soil assist the crop to resist attack, but the practice of intensive cultivation over Fig. 4.—Wirucor1us, t/(c [117'1'17' of (Vic/c Italics. From nature. Slightly enlarged. a series of years was shown by Roebuck 1 to reduce the period of tenancy of ploughed land by \Vireworms from five to three years. The infested ground was either continuously cropped by hoed crops or frequently cultivated in the brief intervals between successive crops. 3. Choice of Crop—In normal times the farmer may select one of several more or less resistant crops, such as peas, 1 Roebuck. A., 1924. “ Destruction of \Vireworms.” Jour. Min. Agric., Vol. xxx, pp. 1047-1051. INsno'r AND o'rnnn rns'rs ow 1939. 97 beans, mustard, rape and flax, for sowing on wireworm— infested land. At the present time, however, the national interest must outweigh all other considerations, and his choice will be restricted to more valuable, but less resistant food crops. such as wheat, oats, and potatoes. Even if they should fail as a result of severe wireworm infestation, part of the loss at least may be redeemed by resowing the land with roots or kale, which will thus escape the spring period of wire‘worm activity. As a matter of experience anxiety in regard to the success of winter wheat on infested ground enables it to resist heavy attacks, especially when the soil is rich and well consolidated. In districts where the Wheat Bulb Fly is troublesome, following grass with winter Wheat will be all to the advantage of the crop. The fly, which is active from July to September, selects for the laying of its eggs the soil of a bare fallow or that which has been imperfectly covered by the foliage of a root or potato crop. Wheat sown under such conditions is often badly hit by the maggots of the fly, which hatch from the eggs in February and feed on the plants until May. Thus where the Wheat Bulb Fly as well as the Wireworm has to be considered, it would be well to take potatoes after wheat in the second year after grass. ‘Even when all known precautions have been taken, thin patches due to wireworm attack may still appear in the wheat crop in spring. It has been suggested by Miles that these patches should receive a light dressing of nitrate of soda and then be sown with spring wheat or oats. On no account should winter wheat be sown after a rye-grass ley, unless the field has been ploughed before harvest. ll‘ye— grass harbours the maggots of the destructive Frit Fly, which migrate to the young wheat from the turned-in sod. Rye- grass leys become infested at the time of the corn harvest when the Frit Flies, which have bred on the flowers and grain of oats, fly over to the rye-grass and lay their eggs. A considerable part of the newly ploughed grass land in Scotland will be given over to spring oats. Following grass this crop does best when it is sown in fields ploughed early in the year, so that there is still plenty of turf to serve as food for Wireworms when the young plants are in the process of establishing themselves. In districts where the Frit Fly is abundant it is well to sow oats early in order to give the young plants a chance to arrive at the resistant four-leaved stage before the flies appear in May to lay their eggs on the leaves. To encourage rapid early growth so that the plant may reach the four-leaved stage before the middle of May a light dressing of nitrate of soda should be applied to the new crop, along with sufficient phosphatic manure to obviate the risk of lodging. 1s often unwarranted, because its strong tillering :apacity, |
| Title | Transactions of RHASS Volume 1940 - Page 054 |
