GARDENERS’ QUERIES

Press, Volume CI, Issue 29749, 16 February 1962, Page 7

GARDENERS’ QUERIES

I enclose a peculiar weed which has developed in our vegetable garden. It has quite unusual prickly fruits, and grows about 18 inches tall. 1 have no idea how it got Into the garden. This is the first time I have seen anything like it. (Mrs H.M.S., Ashburton.)

Your specimen is Datura stramonium, the Thorn-apple. This weed has the unusual characteristic you mention —suddenly appearing as solitary individuals without plants being previously noticed. As a weed it has little importance, for it is an annual and easily removed by hand. It rarely occurs in quantity. It is said to have a medicinal value In the treatment of asthma.

1 enclose a sample of tomato disease which has me puzzled. I know potato blight, wilt, and leaf spot, but have never seen the sample enclosed. It is on the lower leaves only, and causes the leaves to yellow and produce large and irregular brown blotcbes, some of them having rings of darker and lighter brown. It is checking fruit growth. (F.G., Collingwood.) This disease is not a common one—Early blight. Potato blight is known as late blight, but this trouble, which can look rather like it at a quick glance, occurs much earlier in the season. It is worst under conditions of high temperatures and abundant rainfall. Control is by the copper sprays you have been using, but spraying must be started very early. This is probably why you have the disease in early leaves, but not later on. It does not attack rhubarb—the sample you sent was a different trouble of no importance.

When do you bud and graft? How can I propagate Lemon verbena? I have an old bush which has to be moved and would like to raise a new plant. How can I control horseradish? (Mrs H.M.K., Harewood.)

Budding is carried out between the end of December and early March, and grafting in October. Lemon-scented verbena (Lippia citriodora) is easily raised from softwood cuttings at this time of year, or hardwood cuttings about May. Horseradish is difficult to control, since ft propagates itself from every little bit of root left in the soil, and digging out or hoeing over has little effect unless persisted with If you can apply hormones without contacting other plants, then 2.4. D will eradicate it if applied now and when regrowth occurs next spring.

1 have a three-year-old grape vine which Is bearing for the first time. Lateral growth has been quite extensive, and stretches about 10ft on either side of the main stem. As all the bunches are adjacent to the main stem I am wondering if I should check the lateral growth. Would it assist fruit growth? Also, does a grape vine need liberal watering? (E.J.H., Avonhead.)

Summer pruning of vines Is sometimes very desirable. Actually. every case should be considered on its own merits, for growth is a guide to the effectiveness of your winter pruning, too. Good cropping and weak growth indicates inadequate winter pruning, whilst poor cropping and very vigorous growth indicates too severe winter pruning. In your case, where you are getting good growth and good cropping, then the removal of 2ft from the ends of the canes would allow more light and air to get to the fruits. Fruit colouring will occur whether you prune or not. despite common belief to the contrary. Even the most severe pruning should always leave sufficient cane to carry at least eight or 10 leaves beyond the fruit truss This pruning will have little, effect on fruit growth. A vine should not have too much watering Sufficient water needs to be present to supply growth requirements, but excess after this will delay ripening and reduce the sugar content of the fruit. The treatment of indoor vines is quite distinct from. outdoor vines which have been discussed here. Could you supply planting, growing and blanching Instructions for celery? (A.M., Shirley.) Self-blanching celery Is spaced seven to eight inches apart on the square, in beds up to 4ft wide, whilst green or pink celery is planted in rows 3ft to 4ft apart, at an eight-inch spacing. Double rows are sometimes used. Growing requires adequate moisture, and a good supply of food, preferably given in the soil before planting. February is very late for planting; December or January are better. Blanching is only needed with tall green or pink celery.

Earthing up is a' common practice, but you may prefer paper collars, or drainpipes instead. Self-blanching celery will benefit from the use of eight-inch boards pegged vertically at the side of the beds. A month to six weeks will be needed to blanch tall green or pink celery adequately.. Could you please Identify and give the culture of the plant enclosed. (Mrs A.J.8., Granity.) Your plant Is Bougainvillea specabilis. a most attractive climber for districts which are not cold. You could grow it quite satisfactorily out of doors Give it a sunny spot and an archway or trellis to climb over and it will give you plenty of pleasure with its lovely blooms I enclose leaves of a greengage tree with yellow markings between the veins. Is it magnesium deficiency? 1 also enclose an apricot fruit which has completely shrivelled up. Fruits were all right, but on my return from holiday had gone like the sample. What are the ideal conditions for

perennial scabious? (A.S., Redcllffs.) Yes, your greengage has magnesium deficiency. Spray with a 2 per cent, solution of epsom salts next spring when foliage is still young. The sprleot fruit is suffering from brown rot Although the common reaction is for fruit to go rotten and be covered with spores, this dry form is sometimes seen Spray with either thiram or captan at petal fall and about three weeks before harvest. Scabious like a moderately rich soil which is well limed. They are liable to disease 'if exposed to wet soil conditions, and some commercial growers on the Christchurch hills use raised beds to circumvent this difficulty.

1 enclose a carnation plant which is suffering from severe leaf damage on the basal parts. It was raised from an apparently clean cutting, although the parent plant was Infected. Is it a hereditary trouble? (Inter-

ested, Shirley.) Your plants are suffering from carnation leaf spot, and the brown spots with their purplish brown borders on the younger leaves show the trouble quite distinctly. This trouble is controlled by sprays of fermspray Although called a leaf spot, like tomato leaf spot the two fungi are very distinct, and I am rather doubtful whether Shirlan A.G would be effective on carnation. The trouble is not hereditary—it is carried from one generation to the next by spores There are hundreds of sources of infection on the old leaves of the plant you sent. Keep the foliage as dry as possible, and avoid syringing. This is a common means of spread. I enclose leaves from a Rhus typhina tree (Stag’s horn sumach) and specimens of pea. The Rhus Is suffering from browning on the leaf margins. I sprayed it with lime sulphur. Did I do right? The peas shrivel and the leaves turn brown. (Cranford street.) You did not tell me whether the damage was present before you sprayed with lime sulphur or whether it developed after. I believe you have scorched the leaves with the lime sulphur Although this is a very effective fungicide for some diseases it does require care in application. It should not be applied at too great a strength or on a hot, sunny day. Either is liable to cause trouble The peas are suffering from downy mildew This may be controlled with Bordeaux mixture applied at 14-day Intervals on two or three occasions from seedling stage onwards. The selection of plums vou have available is ouite adequate for satisfactory pollination

What Is the matter with my apricot and my pea seedlings? The apricot has blis-tered-looklng marks on the leaves, which turn brown, and the centre of the hole falls out. The peas were dusted with a Thiram-Ltn-dane seed dressing before sowing, but crops still rot off at the base. (Amateur Gardener.)

The apricot is suffering from shot-hole fungus. Sprays of Phygon applied at 1 part in 1000 at three-weekly intervals from blossom time onwards should control this trouble The dust you mention will control one of the foot-rot diseases of peas, that caused by damping-off but it will not control the attack of Fusarium disease. It is possible that this is the trouble you are suffering from, but I cannot be certain without inoculation experiments. A five-year break is required between pea crops to avoid carry-over of Fusarium disease.