Gardeners’ queries

Press, 7 October 1988, Page 10

Gardeners’ queries

I have a black grape which is about 12 years old. The over ail span is six metres of which one half appears to be totally dead. Is this unusual, and should I cut the dead branch right away, or leave it in the hope that it may come away next year. It has been a very good bearer, and of course is pruned annually. A.S. (Chch).

Insufficient information makes it impossible to ascertain the cause of the die-back of part of this grape vine

which leaves room only for conjecture. Apart from disease, the problem may have been brought on by constriction induced by an earlier placed tie or ties cutting the sap flow to the buds, a not unknown misfortune. At this juncture, the dead portion of the vine

should be cut right back to healthy growth. Could you please identify the grey discolourations on these Karaka leaves. This problem started from the base of the tree last year and is rapidly spreading over the entire tree. Growing in Sumner sand, it has always berried well, but not now. “Karaka” (Sumner). Heavy mite infestation is responsible for the greyish appearance of the leaves of this Karaka; some other factors could be contributing to the paucity of fruit. Mite populations can build up very quickly in warm dry weather and cause considerable debility, even death to host plants unless controlled. In this instance, a mixture of summer or all purpose spraying oil plus maldison will give control and should be repeated three weeks later. Alternatively, a specific miticide such as tetradifon can be used. Thoroughness of application is absolutely essential for control of these insects and that means spraying the undersides of the leaves as well as the upper surfaces. A two-year-old rubber tree, around 2m tall when bought has given us much

pleasure. However, recently the leaves from the bottom upwards are turning yellow and falling off. N4w leaves are forming, but they do not droop downwards like the original. I think we have serviced the plant correctly as regards feeding and watering. Your comments would be appreciated. “Rubber Tree” (Ashburton). Drooping foliage is not characteristic of the appearance of a healthy rubber tree. The leaves should be stiffly subtended from the main stem at a slightly upward angle and glossy green to look at. Over and under watering can affect the plant in similar ways. Do not allow the specimen to become dry at the roots but at the same time avoid keeping the rooting medium in a saturated condition. Allow the top few centimetres to become dry before each watering. I am so worried about my camellias as there is no new growth on them. The buds are falling off, and there are hardly any flowers. Once a year I give them a handful of camellia fertiliser, and they were sprayed with oil last winter but they were already off-colour before

that. “Worried” (Chch). Judging by the appearance of the leaves, these camellias are suffering from various cultural problems which together probably account for the unsatisfactory development of the plants. Lack of moisture will not only cause stress in them, but also restricts the ability of the roots to carry out their functions properly such as to absorb nutrients. The handful of fertiliser may be insufficient to supply requirements. Caterpillar damage was noted to be of sufficient severity to warrant the use of an insecticide for control. As the plants are fairly young check that they have not been planted too deeply — when new plantings are made of camellias they should be put in to the depth at which they are in the plant container, no deeper and no shallower. When cultivating the ground avoid doing so in the immediate vicinity of the young plants, but hand weed etc., to avoid damaging the roots near the top. Gardener’s Queries should be sent directly to Mr Mike Lusty, 56 Wayside Avenue, Christchurch 5. Samples should be separately wrapped in a plastic bag with air holes. Provide representative, good-sized samples, and your name and address. A nom-de-plume can used for publication.