§ Mr. Darling
asked the Minister of Agriculture, Fisheries and Food which insect pests and plant diseases of vegetables, cereals and fruits have been eradicated since 1945; which have a declining incidence; which show little change; and which appear to be spreading.
§ Mr. Scott-Hopkins
No established pests or diseases have been eradicated in England and Wales. Colorado beetles entering the country have been destroyed before becoming established.
While it is difficult to distinguish between a real decline in incidence and the normal seasonal and annual fluctuations, it appears that potato leaf roll and strawberry yellow edge viruses have declined; examples of insects that have declined are apple blossom weevil, carrot fly, wireworms, pea moth, and glasshouse white fly.153W
But most pests and diseases show little change over the period; examples are frit fly of oats, codling moth, cabbage caterpillars, tomato mosaic, cereal mildew, and common scab of potatoes.
Progressive verticillium wilt of hops and fire light have spread. Some diseases have increased in relative importance, as a result of changes in commercial practice rather than of wider geographical distribution; apple mildew and gloeosporium fruit rot are examples. Insect pests which have spread include black currant midge, apple Bryobia mite, and cereal and carrot aphids.