Gardeners’ queries

Press, 4 December 1981, Page 8

Gardeners’ queries

GARDENING

by

M. Lusty

My red currants bear well, but every spring after fruit set a jungle of sappy shoots and leaves comes up and cover the fruit, making picking difficult. Should one cut these down before harvest? I have done this and it does not seem to reduce the bushes' vigour. C.H. (Nelson). Pruning induces growth although it can also act as a check if done at the right time. Fruit is produced on predominantly two-to-four-year-old growth. Pruning procedure should be confined to winter operation with no other cutting in the intervening period. Lateral growth should be trimmedback to within two to four buds of the leader and the leaders should be tipped. A general system of renewal of old wood should be carried out on well established bushes so that they carry main shoots of from one to four years old only. Personally, there is growing doubt about the wisdom of tipping leaders unless some sort of spray programme is being implemented as it seems to encourage the entry of the currant borer. I planted Flower of Spring cabbages in September, and although they are growing well some of the leaves have an unhealthy look about them. The cabbages were planted in soil wmch had superphosphate and blood aud bone added to it well beforehand, while the plants themselves have been dusted with derris dust. I enclose a leaf for your inspection ano advice. “Spring cabbage”. (Chch). Again, it must be emphasised that it is necessary to provide adequate and carefully preserved specimens when forwarding samples related to queries, otherwise it usually reduces the task of providing assistance to one of conjecture, as in this case. It often happens that overwintering brassica crops suffer a nitrogen deficiency in spring time and this could be the apparent cause of yellowing of the leaves. A sprinkle of ammonium nitrate along the row and close to the plants may rectify the situation; water in. Could you please identify the condition of my kiwi fruit? It has been sprayed with malathion and

copper-ox but there has been no improvement. The male plant is not as sick as the female. Usually I harvest at least 2001 b of fruit from my vine. I summer prune, and prune again after harvest. This year at sap rise some of the pruning cuts started to bleed — this lasting for a week or so. Because of this 1 have hesitated to prune out badly affected parts of the vine. E.S. (Chch). The crop return from the bearing kiwi fruit should be sufficient to convince any one who nas doubts about the fruiting potential under suitable local conditions. It is also good to know of someone who looks after tneir vine in a proper manner. Unfortunately, however, these plants have suffered the effects of hormone weedkiller drift. This has not completely distorted the foliage, but possibly contributed to other side-effects. There is no way of remedying the situation — it will be a matter of time and patience — and hopefully the plants will overcome the problem. Could you throw any light on what has happened to my young Rhododendron (Virginal)? (Leaves enclosed.) It was planted in April this year bn the north side of a boundary fence in light, sandy (riversand) soil. So far, the new growth has been unaffected by whatever has struck the lower leaves. A garden centre person suggested treating the snruo with Yates’ Carbaryl 80 — this has now been done. But am I on the right track and could you positively identify the disease? R.R. (Chch).

Please find enclosed leaves from a Rhododendron "Pink Pearl.” Could you tell me what is wrong with the bush and what should I do to eliminate it? C.G. (Chch). Both problems on rhododendrons appear to be of physiological origin, and seemingly rather more common this season. Leaves that brown in this wayare usually indicative that the position is unsuitable. Strong winds, too much sun. or cold, wet positions, often associated with a lack of vigour can induce the symptoms mentioned, and these are the points to consider in trying to rectify the problem. Carbaryl is an insecticide for the control of caterpillars only. Ivy has become a very great nuisance and covered a big area. I purchased Dicamba Plus and used a watering can, but it does not seeem to be any good. Please advise me what to use. C.A. (Cheh). Fully established ivy can be difficult to control with the herbicides available for home garden use. and it is doubtful whether dicamba will give the desired results. Suggested treatment is to leave some of the terminal growth of the plant submerged in a strong solution of 2,4.5-T with or without the addition of 2.4 D. or in amitroie T, for about one week. This is a safe way of applying hormone or other damaging materials without any likelihood of drift arising. Alternatively, the ivy could be dug out. Some years ago Rachel Carson wrote a book called "Silent Spring.” In this book various chemicals were mentioned, some of which were, as I remember it, malathion, dieldrin, and lindane. In particular she describes the horrifying death of a child whose father had used a spent malathion sack as the seat of a swing. These chemicals apparently remain in the soil at full strength for many years and may enter the food chain, as did D.D.T. In the past all this was academic to me, but now as I have developed an interest in gardening 1 need advice on wbat sprays, weedkillers, etc. to use with safety. Can you help me? F.M. (Chch). - The sale of therapeutants etc. j for home garden use is generally | restricted, and comes under I strict Agricultural Chemicals

Board Regulations. By law. all products sold wmch fall under this category must carry prescribed instructions relating to use and it is up to the users to make themselves fully conversant with these details, particularly about tne rate and orocedure ot application. Indiscriminate use of many things available to us today can lead to problems just as" can happen in the careless use ol weedkillers, fungicides and insecticides. Timing helps to minimise the

amount ot spraying generally necessary in the home garden as much as selecting the right material to do the job most efficiently. Some controls are' more toxic and/or more pesistent than others, and their use means a longer waiting period for edible crops, or perhaps a greater elapsed time before an area can be safely used again. Many firms produce pamphlets giving additional details on their products, and these should be of help to users.