GARDENERS’ QUERIES

Press, Volume CIX, Issue 32221, 13 February 1970, Page 9

GARDENERS’ QUERIES

I have a Poinciana glliiesii growing in my garden against the north side of the house. It has grown into a very bad shape and I would like to know the right time of the year to prune it.—J.F. (Fendalton).

Poinciana gilliesii is the now little used synonym of Caesalpina gilliesii, a plant with very impressively coloured flowers and long protruding stamens. Judging by the specimens seen it does not form a particularly neat or compact plant tending to Ibe rather . straggly Pruning can be done in the winter.

, We have a wettish patch I in the garden from which calla lilies have spread out into an adjoining paddock. These have kept reasonably close together not having dispersed much. All the same they arc a great nuisance. How does one get rid of them?—Wondering (Westland). Amitrole T is recommended as a chemical control for these plants The best period of the year for treatment is late spring to early summer. Re-spraying may be necessary and a wetting agent should be included to the spray.

Enclosed please find leaves off a quince tree. This tree has been in eight years, flowers in spring and towards the end of Novem-ber-December the leaves turn brown, as can be seen on the samples, and fall off. New leaves appear. It has never fruited. Eventually new leaves also brown and

fall. Could you please explain the reason?—M.B. (Ashburton).

The discolouration of the [leaves is caused by fabraea !scald, a fungous disease which [attacks only the quince, pear and hawthorn. Failure to control it results in an annual carry over followed by reinfection in the following spring. Control should consist of spraying, preferably to proper schedule, using a fungicide such as captan during the season and bordeaux mixture or lime sulphur before leaf fall. Some thinning of growths is also recommended in winter. Quince sometimes take a while to come into fruiting but yours should have had a crop by now. Disease can infect the fruit quite severely. Could you tell me what is the matter with my Victoria plum tree? Half the tree has these silvery coloured leaves, the other half is a natural bright green?—L.J. (Christchurch). It would seem that silver leaf has infected your tree. To be absolutely sure check some of the wood away from the tips of the branches to see if it is discoloured or not. Infected wood will be stained. The extent of the disease on your tree would probably preclude the only possible remedial treatment—cutting out the diseased limbs. Eventually the whole tree will become infected and you will have to dispose of it.

I wonder if any readers have the same trouble 1 have experienced. As is my usual practice I made successive sowing from one > pound bags of Greenfeast peas from early spring onwards and the germination percentage was so poor that most of them were hoed out to make room for a more viable variety of vegetable seed. Everything else in the garden is lovely. M.B. (Christchurch). Possibly poor drainage could be singled out as the chief contributory factor towards seed losses. Germinajtion failure of pea seed is usually traceable to one or even a number of factors. Wet, cold soils or those which receive excessive moisture either from heavy rain or by artificial means directly after sowing are likely to re-' suit in poor germination.' Likewise a temperature below | • 41 deg. F can greatly in--1 hibit germination. Damping ; off disease can cause seedling | s losses and birds and insects ! 1 can also cause losses. It is . preferable to sow only seed

which has been treated with a protectant fungicide. Enclosed leaves from my crab apples which is looking rather sickly of late. It'has not been sprayed or pruned or really had any attention paid to it at all save cutting a few branches off for decorations.—B.C. (Christchurch). Apple leaf hoppers.are responsible for '.the speckly appearance of the leaves—current conditions suit them perfectly. Spray "with D.D.T. or carbaryl. , Can you identify the enclosed plants mostly from Canterbury river beds, i have studied "Laing and Blackwell.” J'N.Z. Flowers and Plants in Colour,” and “Field Guide. to Alpine Plants of N.Z.” and also i “Kock Garden. Plants of the Southern Alps” but can find none of the specimens listed. Would they make garden or rock garden plants? U.T. (Christchurch).

With lhe exception of No. S all the plants are exotics and can be ‘regarded as garden escapes.

i They are: (1) Achillea niillefoliumi (pin form). (2) Hieracium: aurantiacum. (3) Dianthus armeria. (4) Miniulus guttalus. (5) Centaurium minus. (6) Craspedia uniflora. (1) is! difficult to control once [established. “New Zealand! Trees and Shrubs" by Poole and Adams is another very useful book for identification • purposes. It is getting close to the [ time when gladioli should be lifted. Each year 1 have trouble with rotting I amongst my stored ones and would like to know how to overcome this problem? “Glad. Grower” (Tlmaru). Good drainage and adequate rotation of gladioli are: of considerable importance! in securing healthy corms. 1 Only really healthy corms i-should be planted. After lifting the tops should be [burnt and the corms dipped into a fungicide such as captan or an organic mercury compound such as are-

tan which is very good for Jthe purpose. Corms should 'be quickly and thoroughly [dried afterwards and stored [in a cool, dry place.