Gardeners’ Queries

Press, Volume CX, Issue 32351, 17 July 1970, Page 6

Gardeners’ Queries

I have a fruiting cherry tree of unknown variety which bears well. However, every year some of them split, more in some years than in others. Often these fruit will then go rotten. - There does not seem to he any apparent cause for this, though after the crop has ' been picked, it is not unusual to find the leaves getting glassy with black lumps on them. Can you provide an explanation for these occurrences and are they related? “Cherry,” (Christchurch). Splitting and cracking of skin and flesh of cherries invariably is caused bv the advent of rain at the time when the fruit is nearing : maturity. Absorption of moisture is followed by swelling of the fruit. The skin is unable to accommodate the increase and splits. It is then that brown rot may enter and destroy the fruit. The other trouble mentioned is unrelated being the result of pear or cherry slug activity the black lumps to which you refer. Brown rot can be controlled only by timely spraying. using a fungicide such as Captan. Carbaryl is effective against pear slugs. Pleaae could you tell me what to do with my Rex begonia? Every leaf on it has fallen off and even the new little shoots just wither off. I have tried spraying it with Zineb and derris dust. It is in a cool room which only gets afternoon sun.— Garden Lover (Christchurch). Your plant is suffering rather badly from the effects of powdery mildew. This can be a most troublesome disease of begonias and is sometimes difficult to eradicate if very severe. The specific control for mildew is now karathane. You could also sprinkle very finely ground sulphur on

and around the plant. Keep in a warm place. Derris dust is an insecticide, Zineb is a fungicide but not a control for powdery mildew.

I am enclosing the yellow leaf of a polyanthus. Only a few plants are affected. Is it a soil deficiency or do they need spraying?—E.K. (Fairlie). At this time of the year it is often very difficult to diagnose trouble on polyanthus as they, are usually at their worst in most gardens. The leaves from your plants do (not suggest robust health, and r iron deficiency could possibly ’(exist. It is suggested that you J |pull off all the old leaves, ! igive the plants a spray with ! a fungicide and feed with (blood and bone in August. ! (If there is no improvement ■ after about 12 weeks send in ’(some more leaves. Enclosed bamboo, part of ; which is brown and dead looking. It is planted in a ( rather dry place facing north. Also my ehimonanthus doesn’t lose all its leaves half of them colour and fall off; the rest ' are still quite green. It hasn’t yet flowered although about three years old. Is this usual in a young shrub? —R.M. (Kairpoi). The particular plant does not thrive in a dry position such as yours -nd is dying off from a lack of moisture. Moisture is particularly important to get young plants started. ’ I would suggest that you shift it to a more favourable position. It is not unusual for chimonanthus to retain some ; of their leaves for the best /part of the winter. These plants produce their flowers on previous (one-year-old) (season's growth and should have flowered this winter. ’Because of their flowering (habit, any pruning should be done immediately after flowering.