RAGWORT (Senecio Jacobaea) AND ITS RELATION TO WINTON DISEASE.

New Zealand Journal of Agriculture, Volume XXXIII, Issue 3, 20 September 1926, Page 159

RAGWORT (Senecio Jacobaea) AND ITS RELATION TO WINTON DISEASE.

Esmond Atkinson,

Biological Laboratory, Wellington-.

The present article is intended to give a general account of ragwort as a weed, and to sum up what is known about it and its relation to hepatic cirrhosis, or “ Winton disease.” Much experimental work has been done in this direction in New Zealand and in other countries, and a number of reports have been published, but it has not hitherto been easy, except with the aid of numbers of reference-books, even to look through all the evidence collected. With the idea ,of making this evidence as convincing as possible, actual quotations have as a rule been made here from the more interesting of the reports on the various experiments, observations, &c., connected with the disease.

HISTORY OF RAGWORT IN NEW ZEALAND.

Ragwort is a native of the whole of Europe and the west of Asia, except the extreme north of these countries. It is particularly common in Britain, and is looked on as a native' there also, but in all other parts of the world it is regarded as an introduced plant. . G. M. Thomson (“ The Naturalization of Animals and Plants in New Zealand ”) states that he cannot find any earlier record of it in this country than 1874, when he discovered it growing near Dunedin ; but it rapidly increased in Southland, and in Auckland, Taranaki, and Wellington, and is now abundant in a great many parts of both Islands, though it is not evenly distributed throughout the Dominion. Ragwort was placed on the Third Schedule of the Noxious Weeds Act, 1908 (noxious weeds where so declared by local authority), but in the Noxious Weeds Amendment Act, 1910, it was transferred to the Second Schedule, which includes four plants to be considered as noxious under all .circumstances — namely, blackberry, Canadian or Californian thistle (Cnicus arvensis), sweetbrier (Rosa rubiginosd), and ragwort or ragweed (Senecio Jacobaea).

DESCRIPTION OF THE PLANT.

Ragwort is a perennial herb springing from a thick rootstock with abundant shallow roots. There is no tendency in the rootstock to creep,. and this means that one plant is not capable of forming a large patch like Californian thistle, for example. This fact is of importance in considering the different ways of getting rid of the weed from an infested area.

The stems are stiff, upright, and' not much branched below, and reach a height of 4 ft. or so. They are strongly furrowed, but this is not always conspicuous, as they are very thickly clothed with leaves. The leaves are what is known as pinnatifid—-that is, so deeply cut as almost to be compound, the ’ segments in the case of ragwort being themselves crisped and deeply cut along the edges and strongly overlapping, while those at the tip of the leaf are united together to form one segment much bigger than any of the others. In colour the leaves are dark green above and rather paler below. Some spring from the roots and have quite long stalks ; others spring from the stem, and

these upper ones have no stalks but clasp the stem closely. -There is a wide range of variation in'the outline, &c., .of the root leaves on different plants. If two extremes are taken, it is very hard to believe that both can really belong to ragwort. Some plants are smooth and hairless, while others are more or less clothed with cottony hairs, particularly under the leaves and where they join the stems.

In the flowering season (which lasts normally from February to April, though it may be much longer) the stems branch very much above, the flower-heads being arranged in what are called corymbs large clusters in which the flower-stalks spring from different heights on the stem —but are all cut off at the same level, and consequently form a flat-topped bunch (Fig. 1). The flower-heads are about % in. in diameter, bright yellow in colour, and with from ten to fifteen conspicuous spreading rays. The involucre or cup underneath the flower-head is made up of narrow green bracts (scale-like leaves) with black tips. The achenes or “ seeds ” are of two kinds in each head—those from the ray florets being smooth, much curved, and angled in section, while those from the disc or centre are hairy, straight, and nearly round in section.

There is really no other weed of roadsides or of pastures with which ragwort could be confused. There are one or two native Senecios which are a little like it in some ways, but these are only to be found in situations that are quite different in character.

POSITION AS A WEED.

' Ragwort is negligible as a weed of arable land, as it is not capable of surviving continuous cultivation ; neither is it to be feared in firstclass grazing-country where a close permanent turf can be maintained. It has been pointed out that the root-system is not an aggressive one, although a plant cut off at the ground-level is capable of regrowth; but, on the other hand, the seed-dispersal system is an extremely aggressive one. The inflorescence is very well developed (heavily infested ragwort country is a blaze of yellow in the summer), the “seeds ’’are small, and the pappus or down large in proportion. The weed is most dangerous in country where the soil is comparatively light, and where there is a tendency for the turf to break up in the summer, leaving open spaces ready to receive the seed as it falls. Top-dressing under such circumstances is worse than useless as a means of control.

From what has been said it will be seen that the chief means of spread of the plant has been through the agency of the wind from one area to more or less closely adjoining ones, though the seed sometimes occurs as an impurity in lines of agricultural seeds, a small amount being found, for instance, in southern Lotus major.

RELATION OF RAGWORT TO HEPATIC CIRRHOSIS IN CATTLE, HORSES, AND SHEEP. '

In some old English herbals ragwort is called “ staggerwort ” or “ stammerwort ” —names which are at least suggestive of the plant’s not being entirely innocuous when eaten. In his “ Principles and Practice of Veterinary Medicine,” Professor Williams described cases of what he called “ stomach staggers ” in horses, in which many of the

symptoms appear very much like those that have since been met with in Winton disease. He says that the disease “ raged in the south-west of England and Wales in 1800 and 1819, the summers of which were hot and dry, prevailing most commonly amongst horses in low, wet pastures where the grass was rank. It was supposed to arise from their eating ragwort or staggerwort. (Senecio ’ Jacobaea), but of. this there is no absolute proof.”

In Canada a disease of cattle very similar to Winton disease in New Zealand had been known for many years previous to 1903, when experiments were carried out (inspired evidently by Gilruth’s work in New Zealand) to discover its cause. The result of these experiments was that the trouble was considered to be definitely due to the eating of ragwort, and the disease, which was formerly classed as contagious, was removed from a list of . affections dealt with under the Animals Contagious Diseases Act. Four experiments were carried out :—•

(1.) To learn if this disease is contagious through the medium of infected stables. The evidence from this experiment was entirely against the idea of the disease being a contagious one.

(2.) To decide whether the disease is caused by the ingestion of ragwort (Senecio Jacobaea). Sixteen young animals housed in a new stable were tested with various amounts of. the weed, and three of these died of typical “ Pictou cattle-disease ”■ (as it is called in Canada) in less than a year.

(3.) To ascertain if the feeding of ragwort (cured by itself) would produce the disease. Two healthy young animals were used. One was fed twice daily on chopped ragwort with very little bran, and died of the disease in eight months. The other, which was kept as a control, remained healthy.

(4.) A contact experiment, to ascertain whether the disease is contagious by direct contact with animals affected with the malady. After three months the animals experimented on were in good health and fine condition.

In South Africa a complaint exists known locally as “ Molteno cattledisease.” Experiments were carried out (in this case also ■ apparently as a result of the successful New Zealand ones) and showed a South African plant (Senecio Burchelli), allied to ragwort, to be the cause of the trouble:

A disease .having the symptoms of hepatic cirrhosis has been reported from a number of States of America, and from Germany and Great Britain.

HEPATIC. CIRRHOSIS IN NEW ZEALAND..

In 1903 Gilruth reported that for at least twenty years the disease had been known as. the most deadly one attacking horses in Southland. A full account was given by him. at this time of the symptoms in horses and cattle, a few of the more marked ones in.the case of the former being a weak, staggering, swaying gait, yellowness of visible mucous membranes, dark urine, and sometimes frenzy followed by unconsciousness. In cattle one of the first symptoms is a diminution of the milk-supply and an acrid flavour of the milk, making it useless for butter ; others

are a peculiar odour of the skin, rapid emaciation, and chronic diarrhoea. Both horses and cattle show, port-mortem, yellow bile-stained tissues, and the liver almost always in a state of chronic cirrhosis.

Ragwort was long suspected as a cause of the disease, but the earlier experiments seemed not to confirm this, and attention was diverted from the plant for a time. Exhaustive experiments were made to test if a living organism was the cause. Gilruth says regarding them : “ All the experiments were abortive so far as any pathological results were concerned, and it was consequently considered that, taken in conjunction with previous experiments, they effectively disposed of the. possibility of the cause of these cases of hepatic cirrhosis being due to any bacteria or other organisms to be found in the liver or the alimentary tract.

: On the occasion of the Auckland outbreak of 1901 attention was forcibly called to ragwort, which was particularly abundant that year on the block where the disease showed itself, and the presence of which was most marked in two other disease-infested places—Southland and Nova Scotiaalmost the only thing common to three widely differing farming-areas.. Suggested by this fact, a series of experiments- was carried out : *■- ■ • .

’ (1.) Two well-grown six-month calves were fed on a daily ration of 6 lb. ragwort, 2 lb.' bran, 2 lb. chaffed oaten sheaves. Feeding began on 31st March, 1902, and continued till 17th April, when the calves grew dull and sleepy-looking, and were turned out on turnips and young oats. No. 1 died on 27th April; No. 2, on 29th. Cirrhotic liver was shown to be present in both cases.

(2.) Two cows and a horse were fed for three months on chaff made from naturally dead ragwort, one cow being given 1 lb., the second 21b., and the horse f lb. per day— all cases mixed with' other fodder. After three months the cow fed on 2 lb. per day was killed and'examined, and proved quite normal. The horse and the other cow were still so a year later. ' ' '

(3.) To test the effect of green ragwort on stock a 5-acre paddock was fenced in on the Hanga Block, between Okoroire and Tauranga, and horses, cattle, and sheep put on it. The paddock was thickly infested with ragwort, which had previously been eaten off by sheep. First some cattle died, then a horse, the sheep escaping. The livers were forwarded for examination and all showed symptoms of cirrhosis.

(4.) An aged light gelding was fed on oaten chaff and on sun-dried ragwort made into chaff, besides a liberal supply of good hay. The feeding continued from Ist July to 22nd September, 93 lb. being given altogether. The horse died on 24th September with all the symptoms of the disease. ' - .

It was at about this time that the administration of strychnine was first found beneficial, though only temporarily so.

EFFECT OF RAGWORT ON SHEEP.

The statement was made by Gilruth that sheep could resist the action of the Sen&cio poison to an indefinitely ’ greater' extent than cattle or horses. During the period that the horse used in the foregoing experiment No. 4 was being fed at the laboratory two sheep received daily (as well as their food ration) J lb. of the same supply

of ragwort as that given to the horse. At the end of six months the sheep were slaughtered, and a careful post-mortem examination was made. The liver and other internal organs were found in both cases to be perfectly healthy to the naked eye, and a subsequent microscopical examination failed to disclose any ' abnormality. Frequent opportunities .offered themselves, and were made use of, of microscopically examining the livers of sheep depastured on ragwort country, but no marked pathological changes were seen. .

A flock of 2,000 sheep was put twice on to ragwort, with an interval of three months between. The mob was taken off the second time on account of marked mortality, some showing while they were still on the weed, but the greatest after they had been removed from it. The most noticeable symptom was this yellow colour, the affected animals being referred to as “ yellow sheep.” The conclusions arrived at were that sheep can eat ragwort daily without harm (with very few exceptions) if it does not monopolize the soil, and if there is not too much they will check and even ultimately eradicate it. The reasons for the comparative immunity of sheep are supposed to be (i) that the plant is actually less toxic than in the case of horses and cattle, and (2) that owing to their small mouths the sheep can' pick and choose to a very much greater extent when grazing.

gilruth’s CONCLUSIONS.

Gilruth concluded an exhaustive report on "Hepatic Cirrhosis affecting Horses and Cattle (so-called'Winton Disease),” published in the Annual Report of the New Zealand Department of Agriculture for 1902-3, as follows :

A careful consideration of the whole of the facts at our disposal, I submit, can only lead to one conclusion —viz., that Ssnecio Jacobaea is the ca.use of the disease (hepatic cirrhosis). In this, as in so many other matters, what now seems to have been the obvious was ignored ; not without reason. That this common plant was known to exist, and had been known to exist without detriment, so far as was apparent or at least recognized, to stock ; that sheep ate the weed with apparent fondness and evident impunity ; that no one could ever say he had observed horses or cattle 'partake of the plant when growing naturally ; that it was patent to the most casual observer these animals avoided its ingestion, even when it was almost impossible to do so ; and that Mr. Park’s experiment in Southland, so far as it went, resulted negatively (although slaughter and postmortem were never made). All these facts tended to divert the mind from the true cause. In addition, when it is considered that the most experienced and highly trained pathologists in Canada had decided that ragwort was not the. cause of the Pictou diseaseidentical with that known as Winton disease in New Zealand—it was but natural to look for . causes more obscure, and withal offering more interest to the investigator. . . -

Yet, when I had, as I believed, exhausted the possible means of demonstrating the cause to be a living organism, I was forced to again turn my attention to the herbage and to the common weed, which alone, as I have, shown, was the one point of uniformity in three localities so widely divergent in every other respect as Nova Scotia and the two extremities of the colony of New Zealand. That Senecio Jacobaea— commonly known as “ragwort,” “ragweed,” “stinking Willie,” &c. —contains an active . principle capable of producing inflammation, more .or less chronic according to the dose, in the liver of the horse and the ox is, I venture to submit, definitely proved by the experiments recorded. The fact that this weed was known in the days of Culpeper in certain parts by the terms “ staggerwort ” and “stammerwort” is extremely interesting.

Every endeavour should be made by the farmer, the local and the General Government of the Colony, to eradicate this weed, which is not only dangerous

to stock by ingestion, but cumbers the land, rendering it almost useless. Cattle and horses are naturally averse to partaking of the plant, but under certain circumstances, such as a paucity of every other fodder, or its presence in hay or chaff, they commence to eat the weed, and it seems most probable a liking is gradually acquired, the taste persisting evidently after the actual necessity .for the ingestion of the plant has disappeared.

Palliative treatment -has been demonstrated to be of value. Along with careful attention to dietary, strychnine given per mouth or subcutaneously,' as 1 have shown, relieves the acute symptoms of the disease, and renders it possible for an animal's usefulness to continue for several years although affected with a cirrhotic liver. Such treatment is in no way curative as far as the real disease is concerned, and the only really satisfactory course to pursue is prevention by the eradication of the weed ...

LATER OFFICIAL REPORTS

The following extracts from later Annual Reports of the Department are added, since they give a clear idea of the present position in regard to ragwort and its relation to hepatic cirrhosis :

District Superintendent, Dunedin, 1926.

Ragwort Poisoning : In many parts of the district the paddocks are a yellow mass when ragwort is in flower, and there is little doubt that this weed is spreading to a serious extent. A considerable number of cattle, more than we are aware of, also horses, die every year. When grass is plentiful stock do not touch it, but when the grass is scarce . the cattle especially commence feeding on it, and evidently acquire a taste for it. On one farm at Edendale thirty-two cows out of . a herd of sixty died from the effects of ragwort.

District Superintendent, Dunedin, T 925.

Dietetic Diseases : In the Southland district dietetic troubles are prevalent, principally due to osteomalacia, ragwort poisoning, and red water. lam attaching Mr. W. D. Blair’s report, and I quite agree with him that ragwort is responsible for a very large number of-deaths amongst cows in Southland, and the same applies to cows in the Owaka district. It- is quite evident that unless farmers take some effective measures ■ to destroy this weed several districts ■ will become practically useless for dairying. I recommend that a number of ewes be purchased- and put on in the spring ; these by constant nibbling serve to keep the weed in check.

W. D. Blair, Veterinarian, Invercargill; 192

During the' past year numerous cases were reported by the owners of cows in the dairying districts supposed to be tubercular, but on inspection these were found to be affected with ragwort, and in my opinion this weed causes a greater mortality amongst dairy cows than any other condition. On one property which I visited with the Commissioner of Crown Lands the owner informed us that of about forty cows with which he started dairying about three years ago he had. practically lost the lot. One or two animals were noticeably affected on our visit. 'lnspection of the paddocks created no surprise, as it was seen that the ragwort was there-to an extent that made it impossible for an animal- to graze without partaking of the weed. A similar state of affairs exists in the paddocks throughout the dairying districts, and until measures are taken by the owners to rid the paddocks of the weed losses will continue. Few cases of the acute form of ragwort poisoning came under notice; practically all the cases assumed the chronic form, the animal gradually wasting away —in other words, becoming a “ piner.” ' . . ' ;

District Superintendent, Christchurch, 1925

Some ragwort poisoning occurred in the West Coast area, and as the farmers there are inclined to look upon such cases as ordinary losses met with in bush areas and do not report them it is difficult to give an estimate of the approximate number lost. However, lam inclined to think that on one dairy farm six cows died during the year from the above cause. lam keeping in. touch with this area, and spreading information in regard to prevention of the trouble;

MEANS OF CONTROL OF RAGWORT.

Compared with many weeds ragwort is quite easy to get rid of. It is of no importance on arable land because ordinary tillage methods destroy it completely. An important fact in connection with ragwort is that though the plant is a perennial and will survive a single cutting of the flowering-stems at the level of the ground, the repetition of this for a few years kills the whole plant without the need of grubbing it out by the root. Obviously a weed with such numerous and easily spread seeds must be prevented from producing them, and as it is quite possible for all the plants of ragwort in a paddock to be' grubbed out and yet to retain sufficient vitality afterwards to infest the, whole of the surrounding country the tops must, be destroyed early in the season.

Although sheep are now known to be affected by the ingestion of ragwort in large quantities, the danger to them is slight compared with that to horses and cattle, and they are known to eat the plant especialty the young crown—-quite readily, while horses and cattle are believed to acquire a taste for it only after they have accidentally consumed considerable quantities mixed with grass in country highly infested with ragwort.

In the various methods of dealing with ragwort that are quoted it will be seen that all its different peculiarities can be made use of against it, and, however abundant ragwort may be on his property, no one need despair of getting rid of it. The following quotations are mostly from the writings of authorities'in the Department, and several of them are actual answers to correspondents who have inquired as to the best

means of dealing with the weed, as published in the New Zealand Journal of Agriculture : “ If the area is not extensive, control by cutting before flowering ; repeat two or three times in certain seasons. On large areas sheep in sufficient numbers control it. Sheep should not be on ragwort for more than a month or six'weeks, or bad effects will result.” “ When there are only small patches the plants can be destroyed by heavy spraying with one of the proprietary weed-destroyers. Where the weed is too plentiful for this method it can be kept under by stocking with sheep, provided the land is sufficiently improved to enable it to be stocked to its full carrying-capacity . . ." " When it is not

. . J O X J possible to stock well with sheep, try frequent cutting of the young plant before ' flowering to prevent growth of leaves. If flowering is allowed and the weed then cut.. down, enough sap will remain in the stem to mature some seed. On small areas pull up or cut below the surface ; or cut down, gather, and burn. This must be done in the early flowering stages and not when the seed is mature An inquiry by a Norsewood settler and the answers published in the Journal may be usefully quoted in full, as follows : “ Will you kindly let me know,” wrote the correspondent, “ the best method of eradicating ragwort, which, is very prevalent in this district. Most of the settlers pull the plants when in flower. In this case would broken roots left in the ground grow again next season ? I notice that when cut off level with the ground the plants spring up again.” . . ' The Live-stock Division (Noxious Weeds Inspection) replied : “ Where ragwort is pulled it generally grows up again from roots left in the soil, as also happens when the plant is cut off level with the ground. The plant, being a perennial, will grow from the same root for three years. It is thus propagated both by seed and roots. Where it is possible to keep the land well stocked with sheep during the early spring months., when the plant-growth is young and tender, no trouble will be experienced in keeping it. in check and eventually in eradicating it. Where the land cannot be altogether given over to sheep, excellent results have been obtained in many parts of the Dominion by grazing a number of old ewes along with the cows on the pastures during the late winter and spring months, these ewes eating the soft crown out

of the plant when it first appears. The ewes can then be sold off fat

in the summer. When neither of these methods can- be adopted, frequent cutting or pulling up immediately before the plants' flower will be found effective. The plants will have to be so dealt with for three years, however, before the • weed is eradicated from the land. Ragwort is a very free seeder, and if it is allowed to flower and seed the ground will become polluted, and will take at least three years to become thoroughly clean again. In the foregoing it has been assumed that the land in question cannot be cultivated. Cultivation soon suppresses the weed, in spite of its perennial character and free production of seed.” ’ . ' Mention is made in the Annual Report of the Department of Agriculture for 1906-7 that one of its Inspectors in the South Auckland District had noticed that “ black caterpillars ” destroyed a large number of ragwort-plants, The writer is indebted to Mr. D. Miller,

Entomologist to the Department, for the following note on this insect (and insects generally) as a means of controlling weeds : “It is often suggested that some insect might be made use of as a means of controlling ragwort in New Zealand. The larvae of the common black and white " magpie moth ” (Nyctemera annulata) —well known under the name of “ woolly bear ”which originally lived on the leaves of several common New Zealand Senecios, is now often seen on ragwort and allied plants such as groundsel (S. vulgaris) and German ivy (S. mikanioides) as well as on garden cinerarias. The caterpillar is very often extremely abundant on ragwort, which in some parts of the country is quite eaten down by it. In some years the larvae are much more abundant than in others, this being due to the influence of controlling factors, among which are insect parasites. As a means of controlling ragwort N. annulata is not satisfactory. Too much dependence should not be placed upon insects as a control for weeds, and there is a great danger of widespread damage being done to plants of value by the introduction of any allegedly weed-controlling insects."

While the subject of ragwort-eradiction is being dealt with, H. C. Long, "Common Weeds of Farm and , Garden ” (England), may be quoted. He emphasizes strongly the value of systematic mowing of the plant as a means of destroying it, and states that this method is much used in Canada. He takes the following from McAlpine and Wright (“Transactions, Highland Agricultural Society, 1894 : "The best method' is, when cutting off the heads, to leave a sufficient length of the lower part of the stem untouched. In the autumn, when the ground has been softened by rain and the roots have shrunk and hardened, they may be quite easily pulled out by hand.”

There is necessarily a certain amount of repetition in the foregoing control methods as given by different authorities, and there are also a few points which appear contradictory, but which have been included without hesitation as it must be obvious that there can be no rule-of-thumb method given for getting rid of a weed which, is at home under so many different circumstances.

SHEEP INFESTED WITH LICE.

This matter is dealt with by the Director of the Live-stock Division (Mr. J. Lyons) in his annual report for 1925-26 as follows

Sheep affected with lice are still too numerous, and far too many prosecutions for exposing lice-infected sheep at saleyards have had to be taken. It is the general opinion of the Inspectors in the various districts where this trouble is found that it is attributable not so much to a deficient dipping solution as to carelessness in both mixing and dipping. Inquiries from careful sheep-meh confirm this, and indicate that where the directions of manufacturers of well-known dips on the market are followed no trouble is experienced. It is legally a punishable offence to expose sheep affected with lice for sale in' a public saleyard, and, as the presence of lice can be just as readily ascertained by the owner as by the Inspector who examines them at the yards, it is an. unpardonable act of neglect on the owner’s part not to take proper precautions to ensure that his sheep are free from lice before taking them to a sale. The Inspector has the power to order the withdrawal -of the sheep from sale, and it is a question whether we should not adopt this practice generally, with a view to seeing if any better results will ensue, in place of our present practice of allowing the sheep to be sold subject to immediate dipping, followed by a prosecution.”