At one time this pest became so troublesome that it almost wiped out the narcissus bulbs of the Fenlands. Bulbs so affected become distorted while thebecome swollen and turn yellow. If cut open, such bulbs will show brown areas and be soft to the touch. The blooms will be of poor quality and may be stunted and after a time will fail altogether. If there are any symptoms showing, the bulbs should be dug up during early July when dormant and should then be immersed in a tank of boiling water for three hours at a constant temperature of 110° F. Only daffodils, of all bulbs, may be subjected to the hot-water treatment, for tulips and other bulbs will be damaged at such temperatures. There is as yet no known chemical cure so it is not possible to eradicate the pests still in the ground. The treated bulbs should be planted in fresh ground and in order to keep the pest under con trol, the use of fresh ground every three years is advisable in districts where the pest has appeared even though the bulbs remain in a perfectly healthy condition.
This pest lays its eggs during May on the necks of the bulbs. The eggs hatch into maggots which burrow into the centre of the bulb causing the new season’s foliage to become yellow and stunted. Growers of high-quality varieties frequently lift the bulbs as a matter of course late in July and give them the hot-water treatment, which will kill both eelworm and the grubs of the narcissus fly. Or the foliage of the plants may be sprayed from early May as soon as flowering has ended, using theSodium Arsenate, 4 oz. to 2 lb. Of sugar and dissolved in four gallons of water. The foliage should be sprayed fortnightly until it has died away, which will be towards the end of July.
After much experimental work Plant Protection Limited have discovered an extremely effective method of control by dipping the bulbs, when quite dormant in July, in a solution made up of four pints liquid BHC, one pint of spreader (Agral LN) dissolved in ioo gallons of water. The bulbs should be placed in sacks and immersed for a period of three hours after which the bulbs are spread out to dry. This may be a good method of control for commercial growers, though not yet having tried it I can say no more.
This is a pest that may attack almost any bulb, the mites generally entering the bulbs where they may have become damaged in lifting or through damage by other pests. It is actually during storage that the pest does its work of destruction moving from bulb to bulb. Where possible, the bulbs should be lifted in July, subjected to the hot-water treatment and replanted as soon as possible in fresh ground.
Yellow Stripe Disease.
This is a virus disease which appears in various degrees of distortion. In the worst cases it causes the leaves to be streaked with yellow and brown whilst the buds may not open. There is no known cure for the actual disease, but as it is almost certainly introduced by a mite or fly, it should be almost entirely prevented by using the hot water treatment to eradicate all known pests.
Bulb Rot Disease.
This is much like the mould disease of wood, the bulbs being covered with a grey mould which rapidly rots them away. Bulbs so diseased should be removed and burnt and the bulbs in the vicinity should be removed to fresh ground, taking care not to utilize the infected ground for at least three years.