WEED SEEDLINGS

New Zealand Journal of Agriculture, Volume 69, Issue 2, 15 August 1944, Page 109

WEED SEEDLINGS

CONTROL BY WEED-BURNER

By

S. H. SAXBY,

Instructor in Agriculture, Dunedin.

THE control of weeds is an ever-recurring necessity with farmers, market gardeners, nurserymen, and anyone else who is concerned with the growing of plants. This article discusses a relatively new aspect of weed control by the use of fire, that is, the destruction of weeds in the seedling stage, with the weed-burner as the fireproducing agent.

Just as there are many types of weed. and many types of work involved in the growing of plants, so are there many types of weed control in common usage. The plough, the cultivator, and the bulldozer represent some of the means of mechanical control that are used for plants from the seedling to the fully-grown, mature plant. Chemicals such as sodium chlorate, sulphate of ammonia, and even common salt are used to control weeds in pastures and playing fields. Stock also frequently act as controllers of weeds, goats for blackberry, cattle for bidibidi, and so on. For many years fire has been a very useful agent in weed control. In the early days both tussock and bush which were regarded as weeds in the widest sense fell before Vulcan, the god of fire. Broom, gorse, and other weeds are regularly burnt, the fire being kindled by match, torch, and flame-thrower. First Experiments The subject of fire control of weed seedlings was introduced in this Journal in November, 1942, by Mr. C. R. Taylor, who described the use of a weed-burner for destroying weed seedlings in seed-beds at a Services’ Vegetable Production Unit at Rotorua. Following a consideration of this article several experiments were carried out at a similar unit at Outram, in Otago. The object of these experiments was to decide whether or not the suggestions made in the article referred to could be used successfully for weed seedling control on a large scale. As

the result of these experiments and the following season’s practical experience a considerable amount of .useful information has been obtained, from which it is possible to forecast a number of uses to which the use of the weed-burner can be extended. .The basic principle of this use of the weed-burner is the rapid destruction of young seedling plants while they are small and tender. This use is very different from the use to which most weed-burners and flame-throwers are put, namely the kindling and . maintenance of a fierce fire in a plant of considerable size. This article is in no way concerned with this latter aspect of weed destruction by fire. Ideal Flame For the destruction of young seedling weeds a fierce “oil-less” flame' is required. A flame similar in type to but much larger than the painter’s blowlamp is ideal. A raw,, oily flame should be avoided. Such a flame is likely to do more harm than good, as it may leave a film of oil on the surface of the ground which is liable to damage the sown seedlings as they come through. With an “oil-less” flame and holding the head of the burner an-inch or

two from ground level a complete kill of weeds growing up to half an inch or so in height and in a 6-in.-wide strip may be secured. The speed at which the operator may travel varies, of course, according to existing conditions, but is usually in the vicinity of one and a half miles per hour or two chains per minute, which is a comfortably slow walk. Provided they are very young and tender most weeds will succ'umb to this fierce flame. Seedlings of many plants, including the following, are killed very readily: Spurrey, fat hen, chickweed, redshank, pimpernel, wild turnip, and wireweed. Mature weeds such as the various twitches,, sorrel, and docks are not permanently affected, as they have a good underground store of vitality that enables them. to recover from what is in effect a surface pruning. On a great deal of country a large number of weed seeds germinate and appear as seedlings some days before the seed that is sown shows up. This is particularly noticeable in the spring when seedlings of spurrey and fat hen frequently provide a green mantle to a paddock before the crop that is sown comes through the ground. This is, of course, due to the fact that the

weed seeds in the ground are usually, and particularly . in the spring, sufficiently moist to enable them to germinate rapidly as soon as they are brought near the surface of the soil. The seed that is sown has to take up moisture before it germinates and is, therefore, several days behind the weed -seeds in appearing above the soil. Time to Burn It is at this stage that the weedburner is used, namely, after the weed seeds have appeared and before the sown seed shows. Within reason the longer the interval between the final preparation of the ground and the sowing of the -seed the more efficient will be the burning; the longer, the interval the more complete is the germination of the weed seed lying near the surface of the soil.

Using the weed-burner as described above will kill the weeds and leave the ground free of growing plants until the seed that is sown comes up. The. whole principle is very simple, but is extremely effective. In practice this' burning has the same effect as that of top hoeing. Top hoeing is a fairly delicate operation involving the running of a light hoe immediately under the surface of the soil before • the seedlings of the sown plants appear. This action cuts or moves the seedling sufficiently to ensure its death. Top hoeing is very effective,' but can be carried out only on an even and dry seed-bed. The weed-burner is effective' on both a fine, dry seed-bed and a rough and wet seed-bed that is not suitable for the use of the hoe. In addition to this the ground can be covered much more rapidly with the weed-burner than is

the case with top hoeing. In windy weather the weed-burner is not as efficient as it is on a calm day.' It should be emphasised that the weedburner does not affect ungerminated seed, as it travels too rapidly for this to be done. Nor does the heat penetrate the soil sufficiently deeply to kill all weed seedlings that have germinated but that . have not appeared through the soil. That the penetration of the heat from the burner through the soil is extremely small can be seen by the following small trial. Place a sheet of dry newspaper on the ground and completely cover it as thinly as possible with fine, dry soil. Then move the burner over it at the speed recommended (viz.: 1| m.p.h.). It will be seen that the paper .is not even scorched. In order to scorch the paper the burner has to be held steady for seve-

ral seconds. This demonstrates that the flame does not penetrate sufiiciently deep to kill any seeds, and that the young seedlings just below the surface of the soil are unaffected whether they are weeds or “sown.” Any delay in the burning until the sown crop appears would lead to its almost complete destruction. Consequently it is absolutely essential that a very close watch be kept on the germination of the sown seed and the progress of the young seedling. It would be unwise to suggest that the burning should be

that subsequent cultivation should not be too close to the “burnt” rows, If the cultivation is close, soil is almost certain to be thrown O n or close to the rows. This disturbedsoil is almost certain to contain seeds ready to germinate wherever they are placed. If

carried out a stipulated number of days after the seed is sown. So much depends on the kind of seed sown, and its vitality or rapidity of germination. Even more important is the condition of the soil and the existing climatic conditions. In very dry weather burning may be delayed for a week or 10 days or even longer, whereas in warm, moist weather which favours germination four days may be too late. Experience and an eye on the seeds is the only safe guide. At the unit at Outram several acres of crop were successfully “burnt” last spring in the manner described. Crops treated in this way include the following:—Onions, leeks, cabbage, silver beet, carrot, parsnip, soft turnip, and lettuce. In every case good weed control was secured. All of these crops were sown in rows, usually 20 in. apart. This left a strip of ground between the rows of some 14 in. which was not burnt. The “burnt” sections remained virtually weed free long after the spaces between the rows had had to be hoed several times. A point worth noting as far as the burning is concerned is

The ground is frequently too wet to hoe, yet the weather is ideal for weeds to grow, with the result that the weeds between the rows become so large that their eradication by the hoe is slow, costly, and sometimes not very effective. The trial referred to consisted of the burning of weed seedlings in between the rows of established plants. A good control was secured, but complete control, particularly very close to the plants, was not possible on account of the damage liable to be done by the spreading flame. In order to overcome this a

they are placed close to the row they will germinate there and nullify, to some extent at least, the effect of the burning. Between Established Plants. In one other direction a small experiment has shown that the weed - burner may be very useful.

two-wheeled carrier for the burner was constructed. While the design of this carrier is subject to considerable improvement the principle involved is the provision of a shield that will travel at ground level between the flame and the plant. Trials showed that this principle is quite satisfactory. The carrier also has; the advantage of making the work' of the operator easier. The continued: and steady holding of the burner places a fairly severe strain on the operator.. In addition to this without the carrier-

the heat generated by the burner causes the operator’s foot to become very hot as it passes backwards and forwards beside the burner. Ragwort Control Another use to which the weedburner may be placed, although not strictly similar to that just described, is the destruction of the mature ragwort plant. The destruction, of any plant or pest should be aimed at its weakest point. With established plants this weakest point is usually during its flowering period when their whole vitality is concentrated in the allessential seed setting. Some years ago when z the control of ragwort was being investigated at Ruakura it was decided to investigate the possibilities of control by fire. The trial consisted of severely scorching a number of plants with a weed-burner. The result was that 93 per cent, of the plants so treated died completely, the remaining 7 per cent, recovering. In addition to this no seed was set by the plants which had been scorched. The mortality rate' secured in this trial was higher than any other yet secured in trials concerning the treatment of mature plants. From the evidence secured it appears that the method offers considerable possibilities for farmers who have to deal .with small infestations of ragwort. Other Possibilities The weed-burner has proved itself to be an efficient and useful apparatus

for the control 'of weed seedlings on a large scale in vegetable production. The question arises, to what other uses can it be put on similar lines? The following came to mind at once and could doubtless be added to very considerably. . 1. The nurseryman could use it for beds planted out with bulbs and similar plants. He could use it for his seed-beds. Where seed is to be sown in trays it should be just as efficient. 2. The people concerned in - the raising "of tree seeds could use it on the rows with good effect. 3. A small-scale trial has shown that it is quite satisfactory in killing seedling weeds in a recently-sown lawn. Although much lawn grass seed remains on the top of the ground the control of the weeds was satisfactory and the burner did not harm the lawn seed.

4. Experience has shown that seedling grasses and clovers are very susceptible to the flame. The burner could, therefore, be used by research institutions that are desirous of excluding volunteer plants from sown plots. 5. There is little doubt that the weedburner could be used effectively by farmers for certain crops, particularly those that are slow to germinate, such as mangolds and sugar beet. For quick-establishing . and rapid-growing crops it is unlikely to be a successful proposition, but for slow-establishing crops such as those mentioned the burner has distinct possibilities. On country that is badly infested with yellow weed (wild turnip and charlock) its use may be effective with a turnip crop. For the home gardener the expense of a weed-burner would certainly not pay unless it . could be used for other purposes as well.

Ammonium Nitrate Fire Hazard

AMMONIUM nitrate is an explosive if improperly handled, but the explosive danger is eliminated if the nitrate is handled like any other fertiliser. It is therefore recommended that paper fertiliser bags should be burnt when empty, as they create a fire hazard, and burlap or cloth bags should be thoroughly washed before storing.

Coccidiosis of Poultry

is one of the most destructive diseases of poultry, and is probably the most prevalent infectious disease attacking poultry in New Zealand. This disease has been reported from many districts in both islands, and the annual loss among infected birds is heavy. It is, therefore, of considerable importance that poultrykeepers should be able to recognise an outbreak of coccidiosis and to know what steps to take to bring such an outbreak under control. ' How to Recognise Coccidiosis There are two main forms of cocci-: diosis among poultry. These forms may be distinguished by poultrykeepers according to the age of the birds attacked. The first, or more acute, form attacks young chickens between the ages of approximately two to eight weeks. This is referred to as caecal coccidiosis, as the internal parasites causing this disease attack mainly the two caeca or blind guts. Often the first sign of trouble is the presence of one or more dead chickens in a pen, and later the remainder become loose in feather, tend to huddle together, droop their wings, and close their eyes. A careful examination of the pen will reveal droppings containing blood. If a dead chicken is opened the caeca will be found inflamed and distended with blood. In outbreaks where the disease is less acute birds may not die so rapidly, and merely show ruffled feathers and general unthriftiness; On opening such birds it is often difficult to detect blood in the caeca, although they are usually enlarged. In these circumstances dead birds should be forwarded to the laboratory (see address at end of article) for examination, and a definite diagnosis of the trouble obtained. The second form of coccidiosis is encountered in older birds, and is not so easy to recognise. This form usually attacks well-grown pullets before coming into lay or when they have been in lay for a few weeks. Birds so attacked show signs of looseness of feather, a false moult, or a drying-up of the comb. These symptoms may be accompanied by lameness in one leg and a loss of eye colour. If such birds are left in the pen they lose condition and gradually “go light.” While mortality is not necessarily heavy, birds affected in this way rarely recover, and are a big source of danger to healthy stock. This form of the disease is referred to as duodenal coccidiosis, as the

parasites attack the lining of the small intestine or duodenum. Unfortunately, it is not always easy to recognise this disease by an inspection of the small intestine with the naked eye. It is therefore essential to send typically unhealthy birds to the laboratory for a microscopic examination whenever this disease is suspected. Of the forms described the second is the most 'dangerous and should be brought under control as soon as possible. Duodenal coccidiosis may mean the loss of many valuable pullets, resulting in a serious loss in egg production. Cause of Disease While it z is not essential that a poultrykeeper should know the complete life history of the internal parasite causing coccidiosis, some knowledge is an aid to understanding why certain sanitation methods are so important in the control of an outbreak of this disease. Such knowledge also makes it easier to understand why the possibilities of successful medicinal treatment are so limited. Coccidiosis is caused by an organism which is invisible to the naked eye. Coccidia are not confined to domestic fowls, but also occur in wild birds and most animals. Fortunately those species found in animals and birds do not infect poultry, but wild birds will occasionally spread the disease by carrying coccidia organisms on their feet. This may account for some of the sudden outbreaks observed from

time to time on new farms and on farms where the disease has not previously been observed. Coccidia pass through a complicated life history, but two main phases of this life cycle are of interest to poultrykeepers. The first stage is when the organisms are living and multiplying in the bodies of infected birds and thus setting up the disease, while the second stage must be completed outside the birds in litter or in the soil over which birds are running. Trhis second stage occurs after the organisms have passed out of infected . birds in their droppings. Healthy birds may now pick up these coccidia-infested droppings when feeding, ■ but these organisms must undergo a . change, which takes from two to four days, while outside a birdfs body before they can infect a healthy

bird. This is of considerable importance, as will be seen later. A further important fact is that during the second stage spent in the soil the organisms are well protected against cold, draught/and heat, and may, under favourable conditions, remain alive for as long as a year. It is also important for the poultrykeeper to realise that while the organisms are living and multiplying within an infected bird they are embedded in and destroying the delicate lining of the caeca or small intestine. Treatment and Control No entirely satisfactory medicinal treatment for either caecal or duodenal coccidiosis has yet been found. Medicines which are strong enough in chemical action to destroy the coccidia will also destroy the delicate lining of the intestine itself. On the other hand, it is thought that if an acid condition is set up in the intestines of infected birds the multiplication of the coccidia is checked, ' while a mild scouring of the bird is set up which causes a large number of the organisms to be carried out in the droppings. , It. has been seen that these organisms are not able to infect healthy birds for two ’to four days after leaving the infected birds, so that if the coccidia are removed by the careful cleaning of the house they can be burnt before again becoming dangerous. It has been found that this method of attempting to overcome an outbreak is more effective against caecal than duodenal coccidiosis. While it is not intended to suggest that treatment for caecal coccidiosis in this manner is always effective, the following method has been found useful on a number of occasions under practical conditions. Success depends to a great extent upon noting an outbreak at an early stage and acting immediately. Confine the young chickens to their brooder house pen and remove all food for 12 hours. Next, supply a liberal amount in ample hopper space of a chicken mash containing 40 per cent, dried milk powder. Leave this special mash before the birds for 24 hours and then remove. Now feed in the ordinary manner for 24 hours, and clean out the pen thoroughly at the end of this time. Starve again for 12 hours, give the 40 per cent, milk mash for 24 hours, and two days later give a second thorough cleaning to the pen. While carrying ; out this treatment kill off any birds which are obviously heavily infected 'with the disease. Such birds are unlikely to recover, and are the main source of danger to the healthy ones. Remember, the whole chance of success depends upon cleaning the pen and equipment effectively after each feed of the milk mash.

Properly soured milk may be used instead of the milk mash described. In this instance the sour milk is given as the only drink available to the chickens for 24 hours, and then a thorough clean-out of the pen made 48 hours after giving the milk. This may be repeated twice, but because of the acid condition of the milk it should not be given in metal drinkers. It is claimed that treatment with vinegar or Epsom salts has a similar effect, to the “milk flush” described above. While vinegar and Epsom salts are cheaper than milk powder, the latter has a very definite value as a food, and is particularly helpful to birds suffering from a check due to disease. The main point to note in this type of treatment is not so much whether milk, vinegar, or Epsom salts is used, but that success depends essentially upon the efficient and regular cleaning out at the times stated. Only by the removal of the coccidia which infect healthy x birds can this disease be properly controlled. Medicinal treatment is rarely satisfactory in duodenal coccidiosis; Poultrykeepers must realise that the best method when well-grown pullets are attacked is that of rigid culling and strict sanitary measures. Any attempt to retain and treat infected birds is not a sound policy, and will in most cases result in greater total losses finally than if an early attempt is made to cull out every sick bird. The infected flock should be confined to their house and the litter changed frequently until the infection dies down. Wire-netting must be placed

in front of and under the perches to stop the birds having access to the droppings which accumulate during perching hours. Drinking and feeding equipment should be kept clean and thoroughly disinfected from time to time. Poultrykeepers who are in the habit of feeding dry mash are advised to use the wet mash system during an outbreak, and all troughs should be picked up and placed out of the reach of the birds immediately a wet mash feed has been completed. Grain should be fed in a clean trough and not in the litter. Treatment of Housing and Runs As soon as a house can be freed of birds after an outbreak of coccidiosis —whether caecal ■ or duodenal floor and walls (for the first 18 inches up) should be scraped and thoroughly scrubbed with caustic soda. If the floor is wooden, this treatment should be followed by a coat of creosote or a mixture of two-thirds creosote , and one-third kerosene. . Care must . be taken to . clean all dirt out of holes and cracks between boards. Where a grass or soil run outside the house is suspected of being contaminated the area immediately around or in front of the house should be heavily dressed with quick lime and dug over. The run should then be spelled for as long as is possible. Prevention While all birds are liable to be attacked with coccidiosis, it is certain

that birds of weaker constitution, whatever their age, are more prone to this disease and suffer most if attacked by it. Therefore, the first essential in prevention is the maintenance of constitution throughout the stock by sound breeding methods and good management. Breeding from poor stock, small for the breed they represent, and lacking in real vitality, is’ the first step towards encouraging an outbreak of this disease. It is also a well-established fact that damp litter and floors give ideal conditions for coccidia, so that for the prevention and control of coccidiosis it is important to avoid dampness at all times in both brooder and laying houses. This rule particularly applies to areas around drinking vessels. As droppings are a source of danger, it will be realised that the large quantities which collect under the perches must intensify this danger where the flock are allowed unrestricted access to such droppings. It is therefore suggested that where coccidiosis has once occurred and may easily break out again the area under the perches should be wired off against the birds in the house. Floor space may be lost, but greater safety is attained. As a safeguard against contaminated runs annual dressings of quick lime, applied in the winter when the run can be spelled, are advised. The draining of wet runs is a further safeguard against outbreaks. Where farms have been free from outbreaks of coccidiosis special care should be taken at any time when fresh stock or hatching! eggs are introduced. The eggs should be dipped in methylated spirits and allowed to dry before setting, while fresh stock should be placed in a quarantine pen for at least a fortnight and be kept under close observation. Where Help Can Be Obtained . The need for recognising the disease as soon as possible and then of acting quickly has already been stressed as an essential in effective control. It has also been stated that difficulties arise in recognising the disease if it is not present in an acute form. For these two reasons poultrykeepers are strongly recommended to forward suspected birdstwo or three if possible — the Chief Diagnostic Officer, Animal Research Station, Wallaceville. A thorough examination will be made and a report sent back to the poultry keeper without delay. If serious losses are occurring it is also recommended that the poultrykeeper seek the services of the local Poultry Instructor by writing him at the Department of Agriculture, Auckland, Wellington, Christchurch, or Dunedin, according to the district. Delay is dangerous immediately.

Management of Ewes and Lambs

With the aid of adequate draining, in conjunction with liming and topdressing and the sowing of seeds mixtures containing superior strains of grasses and clovers, a large and increasing number of Southland farmers have reached a stage where their carrying capacity is 5 ewes per acre or better. Lambing percentages on the class of farm under review would reach 120 per cent, in most seasons.

—» w l nß»ragi <w-<Br''Whi. «•»-*■ mb. .mi. —b ohm » —— By -—■

A. STUART,

Instructor in Agriculture, Invercargill.

UNLESS steps are taken to deal with the problem of twin lambs, this may prove a source of embarrassment to the farmer towards the end of the season, as generally a much lower percentage of these lambs is able to be fattened off the mothers as compared with the single lambs from the remainder of the ewe flock. Consequently many farmers adopt the practice of removing sets of twin lambs from the rest of the flock soon after lambing, and concentrate these lambs and their mothers on paddocks producing the best feed on the. farm. Mr. P. Fleck, Gropers Bush, has adopted an idea for some years now which has proved to be an easy and effective means of separation, and a great time-saver. _ • Catching the Second Twin: A cage on runners and no bigger than a kerosene case, but strongly made, with

sides and end composed of bird netting, is attached to a “jogger” by means of a lengthy chain. At least 80 per cent, of the ewes will follow their lambs as the cage is pulled forward and through the gateway. Ewe Following Caged Lambs: For the ewe that will not follow her lambs Mr. Fleck has made provision also, by carrying in his jogger a special crate as illustrated in the photograph. It is in this crate that a dog is normally carried during the time his services are

not required in the paddock, or until the crate is required for an obstinate ewe. Before lambing commences Mr. Fleck subdivides a good paddock temporarily into three sections. For three or four days, depending on the rate of

lambing, all ewes and lambs specially branded so that the sets of twins can be distinguished are placed in one section under a distinct colour brand, say, red. For the second section another colour is used, and again a change is made for the third section. By that time the first section of ewes and lambs are ready to be moved to the paddock, which will carry them until weaning time. Under this method a twin branded red which has strayed into a paddock holding lambs branded green can be easily distinguished and returned to its mother through the fence, thereby avoiding mismothering. Mr. Fleck has moved 13 sets of twins' in less than one hour from a 30-acre paddock by his method, which saves the farmer’s legs, temper, and time, besides saving the dog. When not in use the cage is carried in the jogger.