Gardeners’ queries

Press, 22 September 1978, Page 5

Gardeners’ queries

There is an area in our vegetable garden with club root in it and I wondered if tomatoes could safely be grown in this slot. Also how long should the. ground be spelled before planting cabbages again and is there a treatment for the soil?—L.A. (Parnassus). Club root is a fungus disease which is specific only to members of the cruciferous family such as cabbage, cauliflower, turnip, kohlrabi. All vegetables outside this group can be grown without fear in soils contaminated by this disease. Club root may remain viable in the soil for up to seven years. Soil sterilisation, using dazomet, will give control but will also preclude the use of the ground for some weeks after. The application of lime at very heavy rates—34og per square metre for light land and 425 g on heavy soils—is of some benefit but it usually takes at least one year before such treatment has any effect and it can have side effects unless the soil is very well endowed with organic matter. Could you please advise whether coal and coke ashes are good for the garden. If the remains from such fires can be used as suggested, how much should be put on to the square yard?—O.P. (Cheh). The use of coal and coke ash is not recommended for applications to any soil in which it is desired to grow plants.

About three years ago we planted a small length of phebalium hedge. Since that time most of them have made very little growth and some have turned a pale colour. They have not been given any manure and the weeds have been kept at bay with the hoe, no weedkillers having been used. Could you please advise how to Improve them?—B.R. (Chch). The hedge plant to which yon are referring to is Phebalium squameum. Phebalium is sensitive to poor drainage, alkaline soil and root disturbance. It would be advisable to check the drainage, give the plants a boost by adding ammonium sulphate at the rate

of log per metre of row, and avoid more than shallow cultivation in their vicinity. We have been plagued more than usually by opossums which are eating the young shoots and buds off many of our fruit trees, some ornamentals and, in particular, the roses. Is there some form of deterrent other than shooting, trapping or poisoning that could be used to save what is left of the new season's growth?—"Wondering" (Sumner). , There is a re pell ant called thiro which is widely used by commercial orchardists against hares and opossums; it is an effective means of control. Last growing season I found that a very high percentage of ' my carrots had a little white caterpillar type grub in them. ; Could you please tell me what '■ it might be and how to stop it coming at them again this r time.—D.E. (Chch). The warm conditions prevailing over much of the main growing season last year was conducive to greater local infestations than usual of carrot rust fly, which can severely damage carrots by their burrowing and feeding habits. The best way to control this pest is to apply a granular insecticide such as diazinon, at the time of planting. The prills should be spread along the drills below the seed. Please find enclosed a branch from a native which has grown up in our garden. It is now as tall as a forsythia and is covered in clusters of buds. Is it a tutu—in which case it will have to be dug out as, they are poisonous. Also is there a way of m—* q a pink cisfus?_ —E.W. (Chch). <Mi The eii~- -d specimen is most probably a hybrid form of Coprosma robusta. All species of tutu (coriaria) and indeed parts of the plant thereof, are poisonous. Established cistus plants are very difficult to transplant even when cut hard back and it would probably be more expedient to buy another one. These plants can be grown quite easily from seed or cuttings taken in autumn.