Gardeners’ queries

Press, 21 February 1986, Page 15

Gardeners’ queries

GARDENING

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Mike Lusty

Enclosed please find a sample of white Cliantbus which, after flowering, has put on this unusual growth. I would appreciate comments and advice about the condition which has occurred over the whole bush, and what to do about it M.E. (ChCh). The manifestations on this clianthus are large galls or witches broom formations caused by the eriophyid mite. This pest can have a devastating effect on these shrubs with possible death resulting if not controlled. Infestations' should be cut out and burned. An application of lime sulphur at the rate of one part to twenty of water has proved effective and should be repeated if further signs of mites are noted. Care is needed in making the application, which should be kept off the tips of the plant as much as possible. Enclosed is a type of oxalis or some such weed that

has completely taken over part of my garden and now appears In the lawn. Is there any way to destroy it, or would covering the area with black plastic and bark be a better way? N.B. (Chch). The specimen of weed is Oxalis corniculate, a taprooted somewhat variable species which seems to be more prevalent this year. It can be quite easily removed with a trowel, or cut off below ground level with a hoe. It is not quite so readily controlled in the lawn but one to two sprays with dicamba plus may do the trick. There is no need to apply polythene when putting down a good mulch. This impervious barrier often creates its own problems rather than benefits.

I have grown onions in the same plot for several years. Each year. it has been, manured with fowl manure as well as turning a green crop into it before planting again. A lot of the onions have root rot now and I would like advice on eliminating this disease. “Onion Lover? (Chch).

It is not considered sound policy to grow onions in the same place year after year as it can lead to a build-up of disease in the soil, irrespective of the amount of soil and plant food provided. It would be necessary to see • the diseased onions before commenting on any possible con-

trol as there are a number of symptoms to which your description could be applied.

We have always had a lovely crop of red rhubarb from a fairly large patch but for the last twelve months or so the number of green stalks seems tobe increasing. It is getting so that it is difficult to pick enough red stalks for. a decent meaL Broken down compost and seaweed is applied. The plants are a good few years old. Also, how long does it take for a Lemonade tree to bear fruit and what is it like. “Curious” (Kaikoura).

The organic material mentioned will keep the soil in good condition but is not likely to provide the rhubarb with sufficient nutrients for its requirements as it is both a gross and responsive feeder. Further, plants tend to deteriorate over a period of years especially if they do not receive sufficient attention and are regularly harvested. Up to Ikg fowl manure per plant, or up to 120 g of a 1:2:1 mix of nitrogen: phosphate: potassium followed by one to two side dressings of 30g ammonium sulphate per year in addition to the organic material already being supplied, should help to redress the situation. The Lemonade, which has a sort of tangy flavour, should commence to flower within two to three years after planting out, much depending on the root stock on which it has been raised.