MORE INFORMATION ON HORMONE WEED KILLER EXPERIMENTS

Bay of Plenty Beacon, Volume 12, Issue 81, 13 August 1948, Page 7

MORE INFORMATION ON HORMONE WEED KILLER EXPERIMENTS

In response to requests for further information about the * effects of hormone weedkillers on various weeds, the Fields Instructor, Mr E. R. Marryatt, has supplied the following additional notes based on experimental work recently carried out by the Fields Division of the Department of Agriculture: Convolvulus: Fairly ; resistant to treatment and usually recovers completely. The abundant pink-flowered form of Calystegia sepium seems to be less resistant than the common “Bindweed” (Convolvulus arvensis). Applications should not be made earlier than December so that the maximum foliage will be present. If repeat sprayings are made, a kill will be much more likely. Oxalis: A temporary defoliation of the plant is usual but recovery is rapid. Buttercup appears to be susceptible to both dust and spray treatments although the sprays are considerably more efficient than the dusts. An effect of treatment on buttercup in one experiment was to reduce the germinating capacity of the seed subsequently set. on plants which were -not completely killed. Docks: About a 60 per cent complete kill can be expected on docks and about one-third of the plants will recover. The best results are obtained when treatment is given to plants which have been allowed to “get away” and the worst results when docks in a grazed pasture or in the rosette stage are treated. Again sprays are more efficient than dusts, but repeat spraying is usually necessary. Germination capacity of seed from treated plants in one experiment was down to 2 per cent. Hemlock: Seven trials with hormone weedkillers on hemlock gave a practically complete kill in five of them. The hemlock was mature in the other two trials, - and in full flower, and although severe damage was done to the plants, they were not killed and subsequently produced seed. A germination test of some of' the seed, however, showed that none of the seed was capable of germination. In two of the trials at least, the kill of hemlock was assisted by the plant apparently hav-

ing been made palatable by the spray treatment and by stock grazing it to the ground. In one of the trials tlie stock were affected by eating the plant, although not fatally, but in the other trial no ill effect was noticed. The possibility of stock mortality following treatment should be noted, however. Sorrel, Pennyroyal and Bidihidi appear to be resistant to hormone weedkillers although there is a possibility that Pennyroyal may be susceptible. under certain undetermined conditions. Fennel appears to be fairly resistant to these materials at the flowering stage but at earlier periods of growth is quite susceptible to sprays. Fla tweeds in Lawns and Pastures: These weeds, mainly Catsear, Hawkbit, Hawk weed, Narrow and Broadleaved Plantain, and Cudweed (Dandelion is very rare in this district, contrary to popular opinion), are cuite susceptible to hormone weedkillers although Cudweed- is the least susceptible. Dusts are sometimes more efficient than sprays on these weeds. Field Daisy is also fairly susceptible. Clovers are particularly susceptible to heavy dressing of hormone weedkillers particularly to Wfeedone. Even light dressings have a depressing effect. Weedone at 31b to the acre has given a 90-100 p.c. kill of White Clover on a tennis court. Grass is rarely affected although if the clover is affected the grass will suffer indirectly. Cereals are also resistant. Susceptible annual crops include all Brassicas, Carrots, Onions, Beans, Peas, Potatoes and Tomatoes and these weedkillers are therefore not very useful in the home garden. The flower garden will also suffer if attempts, are made to kill weeds in it by this method. The old-fash-ioned hoe is still the cheapest, safest and best method for dealing with weeds in the garden. Great care should be taken thoroughly to clean spray pumps which have been used for hormone weedkillers and the attention of those interested is drawn to an article on this subject in the Journal of Agriculture for July, 1948. “KAY” Supreme Open Fireplace Boiler. A new innovation—fits any type of grate. Ask for further information at Cutlers Hardware Ltd. (C. L. Hudson, Prop.) Phone 80.