IMPROVEMENT OF PHORMIUM TENAX FOR THE FIBRE INDUSTRY.

New Zealand Journal of Agriculture, Volume XXVI, Issue 6, 20 June 1923, Page 363

IMPROVEMENT OF PHORMIUM TENAX FOR THE FIBRE INDUSTRY.

INVESTIGATIONS AT MIRANUI.

G. SMERLE,

Miranui, Shannon.

The writer was appointed by the New Zealand Flax-millers’ Association in November, 1921, to carry out investigations into the so-called yellow-leaf disease of Phormium tenax, with the object of discovering its cause and finding means of combating it. The scope of the work also included improvement of the existing poor condition . generally of phormium,* and the breeding .of plants immune to .the disease. The investigation was centred at the Miranui mill and. phormium: areas of the Seifert Company, near. Shannon. • . ■ 1

When commencing the work I realized that to achieve some immediate result it would be necessary to concentrate on ascertaining the factors which give rise to the disease, rather than to discover its actual causal agent. By working on this line, I became of opinion that there are at least three factors which prepare the way for the disease—namely, (1) the , common method of cutting the phormium-plant,-(2) the grazing of cattle in the phormium areas, and (3)'the presence of weed-growth among the plants. . As the .investigation has progressed, however, so has the field for research broadened, and we now realize that combating the- yellow-leaf disease is but one of the ameliorative measures to be undertaken. ■ -

Work of prime importance for the future of the industry is the selection and breeding of the very best varieties of phormium—varieties which will produce the greatest quantity of fibre of the highest quality. We now know that there are great differences in the varieties of phormium, the fibre yield of some of the best being twice as valuable as that from the average. This comparison is based on the varieties already tested; there may be some even more valuable. It is therefore most important to test every variety.

FACTORS INDUCING YELLOW-LEAF DISEASE

Faulty Cutting of the Plant. — Examining the four factors which induce yellow-leaf disease, it is found that the present ordinary method of cutting the plant is the most important. That method consists in chopping down all the fans 5 in. to 10 in. above the ground. As the cutters are paid by the weight they cut, and the butts of the leaves are the heaviest part, they naturally try to cut as low as possible, the only restraint being that the butts must not . show too much of what is . colloquially termed “ rhubarb.” The butt ends of the leaves are of a rhubarb colour, and if there are long ends

with that colour it discolours the fibre when stripping: discoloured fibre is graded lower than a good white fibre.

The present method of cutting was adopted owing to its cheapness. The effect upon the plant was never considered. Why the present method of cutting is so detrimental to the plant's growth is because cutting all the leaf low to the root causes a large injured surfacea severe wound shock— deprives the plant of all its green leaves, without which it cannot assimilate carbonic-acid gas and convert it into starch-sugar When the growth of such a low-cut plant is observed one notices a creamy white centre leaf coming up in the stump of the fan. After a day or two the first day’s growth becomes greenish and subsequently quite green, but for a. considerable time after cutting one can count by the day’s growth (which is green) and the night's growth (which is white) how long a time the phormium has been cut. The markings are quite distinct, and I have by this means counted as many as twenty-six days’ growth in summer-time. . The plant can produce the green colouring - matter called “ chlorophyll ” in light only, and hence the green and white markings in the new leaves. As the plant has to obtain from the -system all the nourishment necessary for its growth until sufficient green leaves have grown to obtain adequate nourishment from the air, the root-system is weakened, and yellow-leaf being a root-disease this method of cutting encourages it greatly. - ....

Cutting away all the leaf not only makes' the root-system subject to 1 disease, but also encourages all possible leaf-diseases on the new pale-green leaves. ' These have no bloom ' (the waxy matter on the epidermis) to protect them, as old leaves have. Altogether the present method of cutting is very detrimental to the growth of.the plant, and the sooner it is abolished the better it will be for the fibre industry.

Grazing of Cattle.— grazing of cattle among phormium is also detrimental to the plant’s growth, because the cattle chew the leaves and pull out the centre leaf, which delays the growth of new leaves from three to four months. The constant jerking of the leaf while the animal is chewing tends to injure the tips of the embryo fans in the sheath, and in consequence they become affected by diseases and never come up. The function of the gum in the plant is to lubricate the sheath, but that . does not . protect all the embryo fans from , being wounded by the constant jerking. It is known , to all experienced workers that phormium does not thicken up where cattle are grazed, although they usually are not aware of the cause of this.

Weed-growth.— A growth of.’ weeds among phormium crowds the plant and. absorbs the light and air which it would utilize for its better development. I have compared the fibre-content of plants grown close to a fly-line* in the open with that of plants of the same variety grown in the shade of willow-trees. The plants which grew in the open produced over 16 per cent, of finished fibre, while those which grew in the shade produced only 12 per. cent. Moreover, weeds interfere with the cutting of the leaf, and so increase the cost of that operation, and they also occupy land where phormium could grow. . .

SELECTION AND BREEDING-WORK.

Besides studying the factors which are detrimental to the -growth of the phormium-plant I also selected in the Miranui and Whitaunui Swamps over eight hundred apparently healthy plants for the purpose of observing their growth and disease-resistance, also to obtain seed from the healthiest-looking individuals in the most diseased areas. For this work a nursery area of about 4 acres was measured and fenced off. About an acre of this is on a fairly high terrace ; the remainder of the area comprises the terrace slope and a low-lying swampy area. The nursery is situated close to the main road between Palmerston North and Wellington, about two miles north of Shannon. The portion on the top of the terrace is subdivided into twenty plots. Some of the plots were manured with different fertilizers or a mixture of fertilizers, and some were left without any manure, as checks.

The phormium-seed was sown at intervals' of a month, in order to ascertain the best time for sowing. As the land was not ready

in March a small plot was sown below the Miranui mill. In the nursery, plots 1 to 4 inclusive. were sown on 9th June plots 5. to 8 on 10th and 21st July ; plots 9 to 12 in September ; plots 13 and 16 early in October ; and plots 17 to 20 on 19th October.-

I selected seventeen varieties of phormium in the Miranui and Whitaunui Swamps. As these varieties are not yet thoroughly studied and compared, they have been given tentatively numbers for distinguishing purposes. I also obtained from Mr. Pickett, Whitaunui, a variety of mountain-phormium ; from Mr. P. Rikihana, Otaki, two varieties aho and whenu; from Mrs. John Field, Paraparaumu, one variety— ; and from Mrs. W. Simcox, Otaki, seed from a “bronze” variety, and plants from three different varieties, which are not yet compared and identified. As the plants were not seen, examined, and compared when in flower, the identification and description are not complete, and there may be two or three similar varieties. ' •

A number of plants selected for disease-resistance by Messrs. R. Waters and E. H. Atkinson, of the Biological Laboratory, Wellington, were also received, but are not yet large enough for the various tests. They will be reported on later. - ;.

A considerable • proportion of the seed sown' in the nursery was selected with a view to ascertaining (i) to what extent cross-pollination takes, place between the different varieties;. (2) whether seedling plants are ' more vigorous growers than plants grown by vegetative reproduction ; (3) whether the seedling plants keep as healthy or healthier than. the parent plants. . The parent plants are all marked and kept under observation. A few of them are planted in the nursery on the slope of the terrace. ■

There are also planted two rows of badly diseased plants. The plants in one row were sterilized for half an hour in a corrosive sublimate solution of 1 in 800. In two rows the seed was gathered from. diseased plants to ascertain if there is any difference between seed from healthy and from sick parents. An aggregate of about half an acre was sown with seed. The chief reason for sowing so much was that it is easier to find plants with the desired characters in a multitude than among. a few. . ■

IMPROVED METHODS OF CUTTING. Being • convinced that the common method of cutting is very bad for the phormium-plant’s : growth I .sought to discover a better

practice. To be able to demonstrate to the millers the best way of cutting for the plant's future growth I selected in the mill block at Miranui four plants of the same variety, size, and amount of fans, and cut them on 28th March, 1922. The first one was cut in the manner favoured by the working cutters ; the second in the way the swampmanager likes to cut (at Miranui the phormium has not been cut so low as at most other mills) ; the third 4 in. higher than the second and 8 in. higher than the first plant; and in the fourth the side or mature leaves only were cut.

At present, after a year's growth, the difference is so striking that one can see it from a distance. In the first-cut plant three fans have

died, and in the remaining fans the leaves are small, spindly, affected by disease, and of a sickly yellowish-green appearance. The second plant has not lost any fans, but the leaves are very small and much affected by different leaf-diseases. The third is much bigger than the two first plants, and is very vigorous and healthy looking. The fourth plant, with the side leaves cut, is the best, although the side leaves were cut again in August, 1922.

It may be mentioned here that when I showed Mr. Alfred Seifert these plants, after they had grown for about three months and the difference in the growth could be plainly noticed, he informed me that he had tried (but not followed up) the side-leaf or mature-leaf method of cutting on a quarter of an acre at Piaka, in the Moutoa Swamp, some twenty years ago. Later he showed me a fifty-year-old volume of parliamentary papers in which was given in full the report of the first Commission on the phormium-fibre industry, in 1871. In the report it is recorded that a Mr. Nelson, of Napier, advised cutting the mature or side leaves, but no reason is given for such method.

In order to obtain more evidence against the existing bad method of. cutting I counted the - dead leaves in four-year-old and five-year-old blocks of phormium, and found by a series of twenty-seven counts that where 100 tons of leaf is cut there is about 120 tons lost in. dead leaves. It is easy to understand this.if one is aware that the fan produces nearly every month a new leaf (there is an exception of one

to three months in the year, depending on the variety). The life of a leaf is about one year and nine months at the most.

In order to demonstrate on a more practical scale the importance of the method of cutting I measured off in the swamp, where the cutters were cutting for the mill, plots of acre each for diamondshape cutting and for side-leaf cutting respectively. These plots were cut on the same day as the cutters cut adjoining phormium. The leaves in the plants cut diamond-shape were cut just where they start to separate from the sheath. In the side-leaf cutting the leaves were cut at the same place as in the diamond-shape cutting, except that the two middle leaves and the centre shoot between them were left intact. At date of writing (May) there are on the side-leaf-cut plant four to five full-grown leaves, which have grown since- the cut was made in October, 1922. I also, in November, 1922, cut an area diamondshape with the centre leaf or shoot leaf intact, at the time when -the cutters cut the adjoining phormium.

Mr. ’ Alfred Seifert is the . first miller in New Zealand to definitely adopt the side-leaf method of cutting. He started to cut in this way (for the Miranui mill) on 4th January this year, has kept two. strippers running continuously, and will continue cutting all the year round. Mr. - Seifert’s opinion is that, taking into account the- increased yield obtained by side-leaf cutting, it is commercially advantageous to adopt this method. ■ By side-leaf cutting it is possible to harvest three times more phormium in four years from a given area than by the old whole-sale-chopping method. There .are also other advantages of side-leaf cutting which may be dealt with later.

FUTURE WORK AND POTENTIAL RESULTS.

There have . been tested at the Miranui ’’ mill twenty-two varieties of phormium, among which the fibre-content varied from 2-5 per cent, in No. 10 to 16-8 per cent, in No. 12 in those from,Miranui and Whitaunui Swamps, and up to 18-8 per cent, recorded for the “ bronze ” variety (see preceding table). .

. Dr. B. D.. Cross has identified forty-two varieties of phormium, and the Maoris about sixty, so there are from twenty to forty varieties to be tested yet. There may be -varieties which greatly exceed even the above-mentioned 18-8 per cent. Numbers 1, 2, 12, 13, 14, and 15 seem to resist the . yellow-leaf. disease, but there may exist absolutely disease-resistant varieties. The next most important step in the investigation is therefore to obtain as far as possible plants of all the existing varieties in New Zealand, also in Norfolk Island.' *•.

In order to make the breeding and selection branch of the investigation self-supporting it will be necessary to plant from 10 to 20 acres of phormium —one-half of that area, to seedling plants and the other to selected plants from the swamp. . The land has to be well prepared before planting, and after planting cultivated as long as the growth of the’ plant permits. This work will',have to be done on proper farming lines on 1 a .strictly commercial basis to ascertain the profitableness of phormium when grown as . other, farm crops. - Once it is practically demonstrated that good, profit can be derived from phormiumgrowing people will start .to cultivate it, and there will be a demand

for good plants. The growing and selling of plants should thus defray the cost .of this part of the work.

Luther Burbank says that no one can estimate the great possibilities of a wild plant before it is taken into cultivation. Our Phormium tenax is claimed to yield more fibre from a given area than any other known fibre-plant. So far these investigations show that there are great possibilities if the plant is cultivated like other farm crops. The estimates are based on its wild state in the swamp and give striking indications. -Assuming that a certain area yields 100 tons of fibre every four years under the present ordinary cutting method and the present average state of phormium swamps, I estimate that similar areas under improved conditions are capable of yielding as follows : —

The highest average yield of phormium-leaf from 1,000 acres in the Makerua Swamp was 28 tons per acre in four years, or 7,000 tons per annum. It takes slightly over 8 tons of leaf to produce 1 ton of fibre, consequently the fibre-production of 1,000 acres under the old methods would be 870 tons yearly. By cleaning the weed-growth out 'of the swamp the fibre percentage of the phormium would be increased to the extent that, the yield ofthis same area , would be 1,064 tons of fibre.■. By planting the same area in the best selected varieties only the yield would be 1,219 tons.' But by employing the side-leaf cutting method the yield in each case would be trebled. Then 1,000 acres in the present state would givfi 2,610 tons of fibre; if cleaned of weed-growth 3,192 tons ; and if the best varieties only were planted on' that area the production would reach the remarkable total of 3,657 tons of fibre per year. By selecting and growing the present best varieties on a 1,000-acre area, and " keeping ■ the plants clean oh weeds, when the phormium was fully' developed it would yield, by cutting side leaves every year, in ten years, according to the foregoing estimate, 3,657 X 10 = 36,570 tons of fibre. A similar area of the present average phormium cut by the old method would not yield as much in forty years. While, of course, there is an element of theory in these calculations," there is strong evidence that such yields may be readily ■ attained in practice.

CONCLUSION.

In concluding this account I have to express my thanks to all those who have so kindly given plants and seed for experimental purposes ; also to Messrs. M. Campbell, Carkeek, Greedy, . and . H. A. Seifert, of the Miranui mill, and especially to Mr. Alfred Seifert, for., their kind help and co-operation in the work of investigation. . If the phormiumfibre industry is put on a" really profitable basis it will be greatly due to Mr. A. Seifert's efforts to ascertain the. commercial possibilities . of the side-leaf-cutting method, this being a matter of prime importance.

* The term “ phormium ” instead of “ flax ” is used throughout this article, in conformity with recent practice in the Journal.

* Fly-lines are -wide cleared tracks through the phormium, upon which tram-lines are laid to carry out the cut leaf. ; -

Note. — Disease-resistance is not recorded in the case of “ tihore,” “bronze,” and “ Waikanae,” these plants not having been under observation while growing.

Variety. Yield of ' Unscutched Fibre. Yield of Finished Fibre. Grade. Diseaseresistance. Per Cent. • Per Cent. Points. I . . . . ■ . . Per Cent. 16-0 Per Cent. 12-2 Points. ’ 70 Good. o 16-1 . 12-2 73 Good. 3 • • 14-8 II-2 69 Good. 4 13'8 10-7 72 Poor. 5 • • 15’2 13-0 69 Medium. 6 17-1 13-6 70 Medium. 7' . • 16-4 13-0 72 Medium. 8 .. .. 19-0 14-2 69 Good. 9 14'9 I2-I 70 Medium. io . . ... .5-2 ■ 2-5 • Reject Good. 12 19-8 16-8 68 Good. 13 . . . . 18-5 14-5 72 Good. 14 • • 17-6 12-5 70 Good. 15 19-8 16-3 70 Good. 16 18-9 15’3 69 Medium. 17 •• .. ' .. 18-o 13’3 69 Good. Aho .. 16-2 II-2 70 Medium. Whenu 20-5 16-8 72 Good. Tihore . . 19-4 15-4 ' 78 Bronze .. 22-0 18-8 69 Chocolate margin 17-8 15-3 71 Medium. Waikanae .. ... 22-4 17-9 68

Most of the varieties were tested for their fibre quantity and quality. A series of six to eight tests for each variety were made, from 12 lb. to 25 lb. being used in each test. Following are the results : —

Condition of Area. Yield by Present Method of Cutting. Yield by Side-leaf Cutting. Tons. Tons. Average phormium area TOO 300 Area freed of weeds 120 360 Area planted wholly in best. varieties 180 . .54° and kept clean of weeds ■■ 180 54°