Gardeners’ queries

Press, 18 May 1984, Page 10

Gardeners’ queries

GARDENING

by

M.Lusty

Coold yon please advise whether it is all right to compost walnut leaves? KJB. (Chch)

Walnut leaves can be safely composted and are of a very high quality. However, in the process of breaking down they produce a slime which inhibits the passage of air through the rest of the materials. For this reason I advocate separate composting. Recently I wrote to you about wood lice in the garden, and you suggested a mixture of Paris green, etc. No-one seems to know what Paris green is, or where it can be procured. Also the quantity of bran was omitted. ALM. (Rangiora). Paris green is an old ingredient of various insect poison baits, and .whereas it was readily obtainable years ago this is no longer so for the simple reason that arsenicals are now very restricted in their use. Paris green is copper aceto-arsenite. 400 g of bran is required to be added to 115 g Paris green, 150 ml molasses and 1.51 water. The omission is regretted.

Could you identify the disease on the enclosed sample of Japanese plum? I also have a miniature apricot which has similar symptoms of pink/ orange colour and holes in the leaves. C.M. (Chch). The discolouration of the leaves appears to be associated with autumn colouring. The holes in the leaves have possibly been caused by shot hole. This fungal infection attacks a wide range of stone fruit and can be controlled by spraying with a copper-based material such as Bordeaux mixture before leaf fall, and

again at bud movement. During the season triforine can be used. Could you please tell me how to get rid of moss in the lawn and also on concrete paths? I have tried sulphate of iron but after a while the moss seems to come back stronger than ever. J.W. (Chch). Moss control is most effective at the time when it is in active growth, such as in late winter to early spring and again in late autumn. Liberal treatment is required to get the application into the mat of growth, and for this reason it can be very effective if done during damp conditions or even at a time when drizzle is around. Iron sulphate in solution is quite a good remedy. Alternatively one of the commercial preparations containing sodium petachlorphenate should be used. Thoroughness in application is essential and follow up may be desirable. Where moss is treated in lawns the dead matter should be raked out, new soil added, and the area resown.

The enclosed plant was dug up in my garden for the first time in 30 years here. I don’t know if it is the answer to

hunger or malnutrition or some undesirable weed. It has a purplish coloured flower on a single stem and clover-like leaves. Over the past five years I’ve had trouble with my onions. They come up but from about three months old they brown and dry off. At this point they can be knocked out of the ground with effort. A whitish growth spreads through the onion even after they have to been harvested and hung up. Could you help

me with this problem? F.P. (Chch). The problem associated with your onions is probably caused by the disease white rot, which not only attacks foliage and roots during the growing season but continues on as a storage rot. Once this fungus has become established it is extremely difficult to control as it becomes residual in the soil. The first essential is to make sure that all infected plant material is removed and

destroyed. Crop rotation is imperative. The proper implementation of a soil sterilant such as dazomet is worth trying. Regarding your plant discovery, it is with regret that your hopes must remain unfounded but the weed, Oxalis latifolia (most probably), is one of the very worst to have in the garden. Be very careful to ensure that when you remove remaining plants that every vestige of bulbil and root is uplifted.