THE GARDEN

Otago Daily Times, Issue 25393, 26 November 1943, Page 5

THE GARDEN

Contributed by D, TANNOCK, A.H.R.H.S.

ANSWERS TO CORRESPONDENTS

" Worried,” Kaitangata.—Your gladioli corms are certainly bad, and unless it was the wash you dipped them in or the exceptionally wet weather, it is difficult to account for the decay. I think you had better wait until you see which are going to grow, and then lift and burn the rest. “ Sweet Pea Problem,” Roslyn.—The dropping of sweet pea buds may be due to too rich a soil or too much moisture at the roots. They will soon grow out of this. In your anxiety to do better than last year, you have possibly used too much manure. It is better to plant in a comparatively poor soil and apply manure afterwards.

FUNGOID PESTS

Last week I dealt with a few of the more common insect pests which attack' I crops and flowers, and this week I intend to deal with the better known fungoid pests and the more usual means of keeping them in check. In the first place, good cultivation, the selection of healthy stock, and vigorous varieties, and reasonable manuring are the most important; also shelter from cold winds, for it is usually the weak and unsatisfactory plants which are attacked first, and the infection then passes to the more healthy. A fungus is a plant, but, unlike one with green leaves, it has to obtain its food from either live or dead vegetable matter, those which live on dead matter being called saprophytes and those which attack living plants parasitea. Most of the parasitic fungi are very minute, and it is only when they reach the fruiting or sporeproducing stage that they become visible to the naked eye, or when they bring about the destruction of the tissue of their host. They are usually ■ known as mildews, rusts, black spots, brcwn rots, or leaf curl, and all we can do is to destroy the spores or to render the plant unsuitable for their growth by certain sprays or dusts, most of which contain either copper, sulphur, or lime. Powdery mildew is fairly common on the young shoots of apples during the spring and summer, and is usually most common when we have cold, wet conditions Some varieties of apple are more susceptible than others. Spraying with lime sulphur at a strength of 1 in 25 when the buds are bursting and at 1 in 120 at intervals throughout the season is a method of checking the mildew. This spray is often mixed with arsenate of lead to control codlin grub, but in small orchards and private gardens it ■ is better 1o apply them separately. Peach leaf curl usually appears in early spring, causing the young foliage to thicken, curl up. and change from green to grey, or sometimes pink. If they arc not affected badly the leaves can be picked off, but advanced cases should be sprayed with Bordeaux mixture or lime sulphur when the buds begin to swell, to be followed by lime sulphur, 1 in 125, after the fruit has set. The curl attacks both the ornamental and fruiting varieties and. like the mildew on apples, is more troublesome in cold, wet seasons.

Pocket or mock plums* is caused by a blight attacking the plum tree in early spring, causing the plums as soon as formed to elongate and take on several shapes. A good spraying with Bordeaux mixture, 8-6-40, during the dormant period is recommended. Apple scab or black spot also attacks pears, and is troublesome as it attacks both the foliage and the fruit. Spraying with Bordeaux mixture, 8-6-40, just when the buds are bursting, and with Bordeaux, 4-4-40, when the blossoms are showing pink, should be followed by spraying with 3-4-40 during the season. Potato Blight Potato blight is a well-known and destructive disease which attacks potatoes usually about the middle of January, and is worst in warm, muggy and moist seasons. It is well to anticipate trouble and to spray second early and main crop varieties with Bordeaux or Burgundy mixture before the first earthing up, and subsequent earthings (three sprayings altogether) at intervals of a fortnight to three weeks. The disease called clubroot attacks turnips, cabbage, cauliflower, and all members of the brassica tribe, and also all weeds and flowering plants of the crucifera order, causing the roots to swell and become malformed. This pest is usually most destructive where the soil is sour through constant manuring, or where there is no room to allow a satisfactory rotation of crops. Lime will destroy the fungus, and an application of crushed burnt lime should be worked into the ground when preparing it for any brassica crop. Hollyhock and chrysanthemum rust attacks the foliage of these plants, especially those propagated by means of cuttings or suckers. Spraying with lime sulphur, 1 in 100, at intervals through the season will keep it in check. It is most troublesome on chrysanthemums in the autumn, when sulphide of potassium, loz in three gallons of warm water, with a little soap to make it stick, should be sprayed on. Rose mildew and black spot diseases are very common, and I have already noticed some signs of it on the more susceptible varieties. It is a disease which should be anticipated, and immediately after pruning in early spring, the bushes, especially the climbers and ramblers, should be sprayed with lime sulphur, 1 in 25. Later on, when the new foliage is attacked, use a strength of 1 in 120, and while the flowers are opening spray with formalin, one tablespoonful to a gallon of water. Colloidal sulphur can also be used. NATIVE PLANTS The coloured manukas and the clianthus are most attractive at this season, and as both are very hardy and not particular where they are planted, they should be used in every shrubbery. The clianthus, which is somewhat of a creeper, is very suitable for clothing a bank or growing over a low wall. The crimson manuka is the best, but the pink Leptospermum Chapman! is also good, as is L. Keatleyi, which has large pink flowers, shading paler towards the edge. There is also the double white (Leonard Wilson), which is very beautiful a double pink which is not so good, and a dwarf one with crimson flowers suitable for the rock garden. The coloured manukas make a useful and beautiful hedge or windbreak, and if pruned or clipped immediately after flowering, will flower again the next season. They are not robbers, and three of the native climbers thrive on them. These are the Clematis indivisa, Parsonia heterophylla, and Senecio sciadophilus. The last is not exactly showy, but it is I interesting to have a climbing daisy plant.