Gardeners’ queries

Press, 26 December 1986, Page 8

Gardeners’ queries

GARDENING

by

Mike Lusty

Could you identify the enclosed specimen from a twenty feet high tree? In full flower, it attracts an enormous number of bees. J.F. (Belfast).

The inflorescence is from Stranvesia davidiana, an attractive ornamental small

tree of Chinese origin. It belongs to the Rosaceae family, many of which are sources of nectar and or pollen, some very much so.

Enclosed are some examples from a Peasgood Nonsuch .apple tree. The leaves are browning off and appear to be dying. The tree has been given an autumn cleanup spray which has been followed up with regular seasonal spraying. Could it be a physiological disease or a potash deficiency, perhaps? M.C. (Chch). The bacterium known as fireblight appears to be well established on this apple tree. The only known control is the application of antibiotic sprays, either streptomycin or a mixture of streptomycin and terramycin. These alternatives have been found to be superior to applications of Bordeaux mixture. Additionally, all diseased shoots should be pruned back to at least 150 mm below the last visible signs of the disease, such wood being fresh in appearance and unstained (brown) in the cell structure. This disease can be spread by means of pruning tools which come into contact with infected plant material and should therefore be sterilised during and after use. Formalin (1 part in 50 of water) should be used to dip them. All pruning cuts should be sealed. Very hard pruning had been carried out on this tree the previous winter. This must be avoided in the coming one.

Thank you for answering my queries last year. Now here are some more. 1. The enclosed specimen is from a shrubby plant, now over ten feet high, which just came

up in the farm orchard. The stems are quite sappy then gradually harden. 2. When is the best time to reduce the height/size of a lilac without forgoing the following year’s flowering? 3. Do you know why the laurel hedge leaves attract such a wide range of insects, including bees and blow flies in the early spring? “Planter” (Cheviot). 1. Elderberry, a useful source of fruit for a wide variety of purposes. Seed is dispersed most generally by birds, which relish the fruit. 2. With regards to the pruning of lilac, it is presumed that the specimen is one of the cultivars of the common garden lilacs which flower on previous season’s wood. The general principle is to remove spent flower heads as soon as flowering is over. The harder the pruning the more it will affect the amount of bloom produced in the following year. However, it frequently is worth forgoing such loss if an old tree requires reshaping or rejuvenation as lilacs are very tolerant to such treatment. 3. At least one of the so-called laurels, Prunus laurocerasus, is a highly regarded source of nectar from its flowers, and sometimes provides an additional source from the undersides of its leaves.

I am enclosing some rose buds and wondered if you could advise why they go brown and dry up instead of opening. Only about one in twenty of the buds open out on this three-year-old bush. 1.8. (Sumner). The failure of these roses to develop further is due to the effects of grey mould. This disease can. become quite persistent under favourable conditions of hijinidity

and lack of control. All affected plant material should be removed and benomyl or triforine applied and repeated over the next few weeks.

Can you advise about this five-year-old satsuma tree? Spraying has been winter oil and lime sulphur in the winter followed by regular applications of maldlson through the summer. The fruit is now scant and of poor quality. Do you think that this tree has a useful, productive future? M.M.

Anonymous queries are generally disregarded as name and address are a prerequisite to this service although a nom de plume is acceptable for publication. Since it is Christmas time this observation is briefly relaxed. Aphids and disease, probably shot hole, have interfered with the well being of this plum. Aphids in particular can be very troublesome on plum trees during the early to mid spring season. Applying maldison on a two‘to-three-weekly interval basis should give control. Most of the available fungicides are adequate for shot hole control. Although satsuma is a self-fertile plum, which implies that it does not need cross pollination, fruit set may be improved if a pollinator is provided: Santa Rosa is the only suitable one in this respect

The genus Furcraea was named after a distinguished French chemist, M. Fourcroy. Currently specimens of F. bedinghays, a Mexican species are at the prime of their frowering. Spikes, composed of pale lemon coloured, bell-snaped flowers, have been noted in excess of 3.5 m in height. The parent peak subsequently dies but suckers provide a , continuing development. 4