Gardeners queries

Press, Volume CXIV, Issue 33454, 8 February 1974, Page 11

Gardeners queries

Can you tell me why some roses never open properly. I’ve had this • trouble with several roses and after giving them a year or two I’ve dug them out. Last year I bought Charley’s Aunt and Bon Soir neither of which has opened. —M.T. (Christ1 church). Failure of rose blooms to open properly can be due to a number of factors, including insect damage duri ing development; the presence of disease, particularly grey mould; strong sun; dryIness at the roots and even a shortage of nutrients. There are also one or two cultivars which do not hold their blooms as well as others but I cannot comment on the tendencies of the above. | A native as enclosed j which is very old seems to be dying. New leaves wilt and there is die back to the branches. Further down the main trunk gum is coming through the bark and in some places the bark is loose around the trunk. As the leaves die and fall off the whole branch seems to die and become brittle. I have cut out most of these dead branches but wonder . whether the tree is just dying or whether there is ! some disease that I can I arrest by spraying or feedI ing or pruning. —J. D. (Christchurch). ; These trees (Pseudopanax iarboreum) are prone to this ! problem and it seems more prevalent on the old ones,! but the exact cause is not! ■known. Whilst complete re-! ; medial treatment has not been found the incidence can be reduced somewhat. All : diseased limbs should be .carefully cut back to a branch junction and any I such areas and cracked regions exuding gum should be painted over with bordeaux paste.

Enclosed are three specimens, rosemary, winter sweet and mulberry'. The rosemary is losing all its lovely new shoots with this trouble. The other two are so pale and yellowish, something lacking in the soil. Both are young and Is this due to disease or ! grow in open positions ; with plenty of water and sun. Can sterilised mushroom compost be stacked in a heap for using later on? It seems a little ! i musty'. — E. W. (ChristI church). j Mushroom compost is ini dined to become musty but Ithis should not detract from : its use and value, it could | be incorporated with other 'material used in composting. The mulberry is infested by mites which would cause the leaves to have a pale colour. Sprav with kelthane and repeat'in 10 to 14 days time.' iThe winter sweet is possibly suffering from a deficiency Jas suggested by the proraiinent veination but just what jis lacking cannot be diagnosed from the sample. The! 'nature and cause of the! I problem with the rosemary | {eludes me but you could try) {spraying with captan. (I) We have a lush growih of dwarf runner beans, but the crop ap- , pears to be being ruined by bees. After being punctured by bees, the flowers fall off and leave the stalks bare. Can anything be done to prevent this? (2) We have a good crop of apricots but the fruit 1

are falling off the tree, often prematurely, with large brown rot patches. Even small patches enlarge rapidly after usable fruit is collected. Can you advise treatment for next year please? —L. J. (Christchurch). From the details given above and without seeing samples of the disease it is only possible to surmise that the infection on the apricots is brown rot. This can be a very damaging, serious and spreading disease amongst stone fruit and where remedial measures are not taken great loss of fruit is likely and this can prevail again in following years. To keep this disease at bay first of all carefully cut out all cankered twigs and branches from which reinfection can occur. All cut surfaces should be promptly sealed with a good sealant. Spraying should be done at leaf fall and again during the dormant and bud movement stages, using Bordeaux mixture. During the season at such, vital stages as pink bud, full bloom, petal fall and thereafter at two to four weekly intervals a fungicide such as captan should be applied. All fallen and mummified fruit on the trees should be gathered up and burnt. Bees do not. bite floral appendages and if the flowers are indeed being damaged in this way then it. will be some other insect. There is no means of protecting the flowers with a spray which will not harm bees. The flowers could he dropping through other causes such as dryness and or exposure to wind.

Ipomoea Lobata (synonym mina lobata) forms an unusual and attractive flowering annual climber. It produces slender racemes of delicate tubular flowers which are initially crimson changing to orange then yellow, and finally white before they droop and fade away.