WEEDS MUST BE CONTROLLED

Press, Volume CXV, Issue 33786, 7 March 1975, Page 15

WEEDS MUST BE CONTROLLED

eeds in the vegetable garden present a neverending problem hut they must be contended with and controlled if the industry of cropping is to be at all successful. If allowed to survive weeds present serious competition! to the vegetables for soil moisture and nutrients—they can suppress sunlight reaching them and can harbour pests and diseases which can readily pass on to the crop. Apart from also looking unsightly such weeds can multiply if allowed to seed and also overrun an area in the case of perennials and those with underground stems. In some cases eradication can be virtually impossible unless really drastic control measures are taken. The use of a good sharp hoe or cultivator or both used every week will nof only make the task of maintaining a weed free area very much easier but will also keep the soil in a friable state. Any form of soil cultivation can be damaging to the vegetable if it is done carelessly. Young seedlings need

only a slight nick in the stem| to wilt and die under most conditions. Many older plants are far more tolerant of such treatment but can be severely ■ weakened by close, deep till-' , age of the soil, which damages or destroys their feeding root systems which radiate from the plant at vary'jing depths and to different I distances. . Tn many cases it pays to resort to hand weeding in the ,i immediate vicinity of the) ! nlant rather than rely on the [ hoe. Little time is lost and) (the action of destroying the) : weedfs) is completely under ! control. This is particularly [applicable to such fleshly [ stemmed plants as cucurbits. Once these plants have developed a bit more they will naturally suppress further ;' weed growth close by by : ) means of the canopy of their lown growth. > Another advantage of main1 taining regular cultivation along and between the rows ? of vegetables lies in the fact ’ that young weed seedlings ! soon dry up in the warm sunshine and do not have to be - removed as is the case with > large clumps of extraneous • growth. i Herbicides provide us with

(another means *of maintaining a good clean vegetable plot. The commercial grower relies very heavily on them for: virtual!}’ total weed suppresi sion in some crops. He has! the opportunity of selecting ) from a range of pre-. emergence and post-. emergence materials, some j of which are formulated for ) a particular crop or perhaps) I certain weeds. In some cases great care is necessary in ■| their application to achieve (the desired effect, and such ' things as the soil type, weed ' problem, kind of vegetable, condition of the soil, and weather may have to be considered. Many weedkillers which may inhibit germination of the weed seed or destroy the plant at various stages of growth are only available in commercial quantities and it )may be necessary to approach a grower friend in 'lorder to get the small quan- ; tity of material required to ’[treat the average home gar- [ den crops. In any case it is advisable to ascertain the residual properties of whatever it is that i is going to be used as some jof them can inhibit the sub-

sequent germination and development of certain alternate crops as long as six months after application. For the very small vegetable garden this could mean planting and sowing for this period is completely restricted.. Where persistent perennials such as twitch and Californian thistle have fully encroached over the area the thing to do is to forget entirely about cropping until they have been eliminated from the ground. It will be found to be a worth-while sacrifice. Amitrole T is a very good control for both the above weeds but in severe infestations it is advisable to repeat the treatment on all i regrowth. Similarly, dicamba offers the best way of countering convolvulus but as this is a hormone, greater care must be exercised in its control. Oxalis is a curse and a problem which requires a contractor to deal with.

Dessicants, preparations such as paraquat and diquat, have their uses, but they are only successful against annuals, having but a temporary effect on perennials. They rely on contact for results, destroying green tissue on which they fall and therefore any drift which may land on vegetables usually causes only superficial damage. Dessicants are useful in stale bed preparations whereby germination of weed seedlings is encouraged and then sprayed followed by seed sowing or planting a day or two later. Simazine is a preemergence residual weedkiller for use in sweet corn and asparagus. Propazine is similarly very effective in carrots ’ and parsnips, while linuron and trifluralin can be used in a number of crops including celery, carrots, parsnips and asparagus. It is very important to observe the manufacturer’s recommendations strictly. If this is carefully followed up the results can be very apparent, particularly to anyone who has not seen the effectiveness of these materials before.