Garden queries

Press, 20 November 1987, Page 18

Garden queries

Could you please advise whether excessive moss and lichens on fruit trees could cause die-back on the branches? Lime sulphur has been tried. A.H. (Tai Tapu). Excessive development of moss and lichens on plants is often a sure sign of a lack of vigour, and can lead to further debility. Lime sulphur, when properly applied during the winter months, normally provides a satisfactory control. It should be applied to the point of run off. The fruit trees should be fed with a balanced fruit tree fertiliser in late August to stimulate healthy and strong growth. Enclosed is a photograph of a Magnolia grandiflora which has developed strange lumps that are more visible on the smaller branches, but also infests the trunk. The tree is about 30 years old, and has been looking sickly and losing leaves for about a year. Is there anything that can be done about it to arrest or cure the problem? L.M. (Duvauchelle R.M.D.). Magnolias generally do not suffer from many complaints. The symptoms displayed by your tree certainly do not indicate a healthy specimen. Apart from the distorted appearance of the wood it also looks to have an unhealthy appearance. It is not possible to ascertain the cause, which may only be possible by an inspection of the tree itself. It does look as though there has been some cutting back from time to time, and at least some of the stubs left have rotted back. A thorough clean up of old growth, stubs, and decaying wood may be of help along with several applications of a copper-based spray.

Enclosed is a sample from my flowering cherry tree. I wonder if you could tell what is lacking, or whether it has some bug that is attacking it? It never responded to several different sprays applied last year. Come spring this year it came away well and then turned to this; another cherry is similarly affected. “Sweet cherry” (Greymouth). This fungal infection, which

causes a “shot hole” appearance of the leaves as well as other symptoms, favours wet springs. Under severe infection, complete defoliation can occur. Thorough over-all application of a copper-based fungicide, such as Bordeaux mixture, should be made during the season, before leaf fall, during the winter, and at bud movement

Could you please tell me why a Golden Drop plum tree drops all its fruit before they get any size at all, going yellow and dull before doing so? This is the third season that it has produced little or nothing. Yet a Burbank near by crops well each year. It had bladder plum badly, but following your instructions on spraying it, it had only two this year and these were picked off. Will I have to spray for bladder plum before next year too? There was a lot of rain when the trees were in blossom. If it would be best to cut the Golden Drop off at ground level, would it be safe to put another plum in its place? I.S. (Westport). The Golden Drop plum is a self-sterile European variety and as such requires the presence of a suitable cross pollinator to produce a crop of fruit. Several varieties are suitable for this purpose, including Greengage, Yellow Magnum Bonum, and President. Unfortunately Burbank, a self-fertile Japanese variety, is ineffective for this purpose and even this plum can respond to the presence of certain other varieties, such as Early Sultan, Purple King, and Santa Rosa. If the Golden Drop is to become fruitful it is necessary to

provide one of the suggested cross pollinators, either as an additional tree or as a graft, otherwise the story of crop failure will continue. Pest and disease control is a continuous matter, that cannot be contained by a once-only treatment. Many of the more prevalent problems such as leaf curl, codling moth, and bladder plum must be dealt with promptly each year just prior to and after the sea-

sonal occurrence to achieve good control.