Gardeners’ queries

Press, 27 January 1978, Page 6

Gardeners’ queries

The leaves enclosed come from an umbrella tree. For the past few weeks leaves have been dropping quite regularly. The young leaves look fresh and green but as they get older they yellow, droop and fall. It has been noticeable that a shiny deposit appears on many of the leaves. What is the remedy?—J.M. (Christchurch). The plant in question is brassaia actinophyUa. The leaves examined showed damage by thrips and the presence of scales was also noted. It is advisable to apply a combination of maldison and summer oil as soon as possible. The shiny deposits, an excres-

cence ot the thrips, will disappear in conjunction with the control of the insects. I have grown gerberas for some years but so far have had no luck raising plants from seed. Is there anything special about it?— "Wondering" (Amberley). There are a number ot points to note regarding seed and sowing of gerberas. The seed does not remain viable for very long after harvest and best results are obtained from that which is sown almost immediately Seed and seedlings are susceptible to damping off and for this reason sterilised soil is desirable. Drenching the soil with 2 per formalin is a good

eent formalin is a goon method but should be done well in advance of sowing. Good drainage is essential and a 1:1 mixture of sand and compost is ideal. Seed should be sown point down with the tail or fluffv end just showing. In cool conditions it may take three weeks or so for germination; at 15.6 deg C. only about 10 days. In the last few weeks the leaves of my grapevine have become completely distorted and appeared to be dying in the hot weather. I have not done anything to it lately other than summer pruning. It was given lime sulphur in the winter and pruned as usual—" Despairing" (Christchurch). The winter spraying was correct and would have no bearing on the current condition This has been caused by hormone weed killer drift to which grapes are very susceptible. There is no cure and it may take many years before it is back to normal.

providing the dose of hormone was not too strong, in which case the vine may eventually die. I have three plum trees, side by side—Shiro, Early Sulton, and Black Doris. Shiro is laden with beautiful plums every year, the other two have grown about nine feet high and never had a plum. What would you say the reason is? —"Plum Grower" (Rangiora). There are a number of possible explanations but some conjecture as to failure to fruit would have been assisted if it was known whether or not the non-bearing plums at least flowered. As Early Sultan and Black Doris are suitable pollinators for each other but not for Shiro. as far as current records show, it would be more logical to expect the first two plums to bear well and the third one, Shiro, to be in fruit. The different flowering periods make some fruit more susceptible to weather conditions which may be detrimental to pollination at the time. An earlier or later flowering fruit may just blossom at a time fullv conducive to both good pollen availability and receptivity of same. Wickson and Santa Rosa are two suitable pollinators for Shiro. Failure to flower does occur with many plants and is regarded as a genetical defect; sometimes plants take very much longer to come into flower or perhaps set fruit and this, too, is but an inherent defect. It mav be added that prevailing weather conditions at the time of full bloom over the past two or three years has been far from good for stone fruit, set.