Gardeners’queries

Press, 27 February 1981, Page 11

Gardeners’queries

please could you tell me if I should let suckers from the raspberries grow? I cut out all the old wood and new ones are coming up about a couple of inches high. I really have enough new wood. When should 1 allow new canes to start for the following year? W® don't seem to get many raspberries, and I thought may be that we allow the new growth to come too soon. A. W. (Chch).

Raspberries throw up sucker growth almost continuously throughout the year, and it is from these that the fruiting canes develop. Fruit is borne only on current season’s growth, and for this reason spent wood is removed, preferablv as soon as the last of the crop has been picked, just -is vou have done. Shoots which develop during the year are generally retained until the winter time, when they are thinned out. retaining only , the strongest at a spacing or 100150 mm apart in the row, presuming the hedgerow system of training is. being used. During the growing season, any suckers which arise too far from either side of the row should be chopped off, unless they are required for replacement purposes. Raspberries respond well to feeding, so the annual application of fertiliser

and organic matter of any description is beneficial. A mixture of blood and bone and potasium sulphate (10.1 byweight at 150 g per 2m of row can be recommended).

More than twenty years ago ■ took a cutting of a red camellia and it grew, it is now more than ten feet high and looking healthy, but has not produced a flower in all this time. Another problem of the same kind Is in regard to my hoya. It is looking very healthy, growing well, putting out new shoots and climbing about twelve feet round the porch. It is planted in garden soil with leaf mould put in recently. M.M. (Chch). -You have certainly beenpatient in waiting for your camelia to come into flower. It does happen occasionally that flowering does not occur on almost any form of vegetation, but usually there is a reason. The suggested . course of action in this case is to wrench the shrub by severing the roots right round it, at approximately 0.6 m from .the base of the trunk. Use a sharp spade and cut the roots cleanly to the full depth of their penetration in the soil: they should be done early autumn. Also do not feed the camellia. With regards the hoya. this plant normally takes a year or two to come into

bloom, but this appears to be very much dependent on certain factors. Plants which look a little sickly and. have been, kept under-potted, though not exactly root-bound, have tended to produce earlier, more and better flowers than overvigorous. glowingly healthy looking specimens. Enclosed is a cutting from a well-established, eight-year-old Seneclo reinoldii, which is one of two separate examples in my garden which have wilted and appear to be dying over the last month or so. The trees have been well watered, and have not been in contact with herbicides. Could you explain the reason for this wilting, and will they recover? The rhododendron leaf, also enclosed, Is characteristic of the whole bush. What is the cause of this? G.P. (Chch). The damage to the rhododendron is phvsiological, and could possibly be attributed to the very warm, dry, and sunniweather of recent.months; the tip burn could well be the result of moisture condensation which has collected at these extremities of growth. Being surface rooting, rhododendrons generally react more quickly to drring out of the soil particularly where the root zone is free draining and without a surface mulch, or much if any organic matter in it. The die-

back on the senecio has been noted on some other species and tends to occur on older growth, predominantly during periods of stress. Just what the cause and control is I currently do not know, but have found that if such affected, branches are cut well back they usually tend to grow again. ■ We have been plagued with an infestation of caterpillars of all types on the geraniums, potatoes, and other vegetables. We have tried Pyrox, Malathion, and Maldison, with no success. Would you please give the names of any new insecticides which . have more lasting effects? J.F. (Chch). - The materials mentioned are indeed short term — two of. them, Maldison and Malathion, being the' same thing — but thev should be reasonably effective for the purpose applied. One of the best materials now on the market for caterpillar control available for home garden use is the wettable powder formulation of acephate. This, systemic insecticide remains effective for up to fourteen days, depending on the growing conditions, and has the added virtue of controlling a wide range of other insects as well. There is also carbaryl of lesser persistence but proven effectiveness a gain t caterpillars.