Gardeners’ queries

Press, 15 October 1982, Page 14

Gardeners’ queries

I am going to plant some citrus trees next winter, and as the place where they are to be planted has a lot of clay in the soil 1 intend to try and improve it by digging a good deep hole for each tree and putting some of my good soil into each. I also intend to add seaweed and cow manure which should have rotted down before planting. I have also been told to add plenty of peat. The drainage is not the best, but if I raised the soil about six inches would this solve the problem? I intend to spray my other citrus trees with copper oxychloride and ortbene. Do I mix the orthene with the copper, and if so how much per gallon? Could conqueror oil take the place of orthene as I think one of my trees has aphids on it? A. B. (Akaroa).

Digging deep holes in poorly drained or heavy soils can often act as a sump, thus creating an even worse situation for the plant in that site. Adding- the organic matter at this time is a good idea, and it should be rotted .down by next winter. Peat is not deemed an essential, and again can be the cause of a problem if the soil is allowed to dry out. Drainage can be improved by forming a raised planting bed. Orthene is incompatible with most inorganic chemicals, and this includes any copper-based material. Maldison could be ap-

plied with copper oxychloride, as could spraying oils, but the latter are not the ideal for dealing with aphids.

Please find enclosed leaves of Rhododendron Christmas Cheer. We shifted it last winter, but just before flowering this year a browning started on the outside of the leaves. The soil is heavyish and has been mulched with mushroom compost. P.S. (Sumner). Rhododendron Christmas Cheer usually presents little problem to grow, but like all plants which require an acid medium to thrive it is averse to alkaline conditions and poor drainage which can be imposed by heavy clay soils. Mushroom compost is not recommended for the likes of such plants because most of such compositions are alkaline. Also check on the depth of planting and exposure to sea breezes.

Enelosed is a sample of one of my plum trebs on which for several years now some of the leaves appear to be distorted. I have carried out a proper sprayprogramme, firstly by spraying with copper oxychloride to bud burst, and when the leaves have started to develop sprayed with Captan and Maldison, then ten days later with Pyrox. M.S. (Chch).

Aphids, and to a lesser extent mites, were noticeable on the leaves and their presence would account for the discoloration and distortion of the foliage. The aphids showed no signs of life so presumably your spraying was effective, though perhaps a little late. The few mites were pretty sluggish and a follow-up spray now with Tredifon. or even all seasons spraying oil, should clear up this problem. Please could you advise what ails our young Norfolk Island pine? We were advised when we bought it that it would withstand the heat, and that it should not be over-watered. It is growing in a tub on a north-west-facing terrace. By the way, what purpose do leeches serve in the garden — I found two in a celery plant? D.M. (Chch). Norfolk Island pine is reasonably tolerant to heat provided it does not dry but when it is used as a tub plant. It should not be over-watered and is perhaps best suited to a position in dappled shade when container-grown. Your reference to leeches has me puzzled, and it is assumed that you may be alluding to slugs which of course will eat a variety of vegetation. Gardeners’ Queries should be addressed to M. Lusty, 32 Brockworth Place, Christchurch 1.