ERADICATION OF HARD FERN

New Zealand Journal of Agriculture, Volume 63, Issue 4, 15 October 1941, Page 313

ERADICATION OF HARD FERN

1111111t1111111U t tmmmum linn 111 ii Dini! mulmi 111 11111 i 111 Experiments in the Southern King Country show that hard fern can be eradicated, and that many areas at present occupied by this pest can carry good productive pastures. Thorough burning is necessary, together with reseeding with a suitable grass seed mixture, followed by topdressing and good pasture management. Heavy stocking with run catle is also essential for at least the first twelve months to crush out any surviving fern.

Fy iiiiiiiiimiiiiiiiiiiiiiiiiiiiiftiiiiniiiitiiiiiii

W. T. BROWN,

Fields Instructor, Taumarunui. E

Successful Experimental Work In King Country

Z~XNE of the first plants to invade ONE of the first plants to invade \_y grass land in most reverted country is hard fern. This fem, which is known by various local names, such as ring fern, silver fern, carpet fern, and, mistakenly, as water fern, usually appears first on the cold, damp faces lying away from the sun, but may also appear on dry, sunny faces. This fern covers large areas of hill country, and causes . considerable loss to , farmers. . Some farmers have been reasonably successful in combating this pest, but many have failed to make any headway against the gradual spread of the hard fern. The fern, which is a surface-rooting plant, is very difficult to eradicate, and although burning has been practised for a number of years, it has proved only a partial success, and the usual result was a regrowth of the fern patch in the form of a. ring, leading to the name ring fern. From the surface-rooting habit of the plant, it is apparent that if it is to be attacked by fire it is necessary to burn the area when the ground is dry and also when there is a reasonable amount of dead leaves to carry the fire and produce a good heat, thus destroying most of the roots. Earlier Experiments Earlier experiments with hard fern were carried out in the Whangamomona County, , and proved that hard fern can be controlled by spraying with one part by weight of arsenic pentoxide and 320 parts of water. This may seem a reasonable method of eradication, but when it is remem-

bered that all water has to be packed up the steepest and most inaccessible parts of the farm it is not surprising that this method of destruction found little favour with farmers. Recent Experiments In 1938 experiments were planned to discover a cheaper, easier, and more practical method of destroying the hard fern and regrassing the reverted areas. A block of 15 acres on the property of Mr. D. F. McLeod, Opatu,. was selected for the experiments, and as this was fairly evenly divided into five blocks by ridges, it was decided to try five different treatments, which are summarised as follows: 1. Topdressing a block with superphosphate and grazing with rim cattle. 2. Burning with a flame-thrower, reseeding, and topdressing. 3. Treating the hard fern with a 5 per cent, mixture of sodium chlorate

and lime; later, when the fern had withered and dried, burning the patches with a flame-thrower, and sowing the burns with a suitable mixture of topdressing with superphosphate. 4. Burning the fern with a “firestick,” reseeding, and topdressing. Treatments 1, 2, 3, and 4 are all applied in the autumn. 5. Burning with a flame-thrower in the spring and reseeding and topdressing. After the first year all blocks were topdressed with 2cwt. per acre of superphosphate each autumn for two years, making three years’ topdressing in all. On Treatments 2, 3, 4, and 5, four plots, each consisting of one burned patch of fem, were pegged. These plots consisted of two good burns and two poor burns on each block, and were used to give a check on how the burns grassed and how they responded to the heavy grazing, with run cattle.

The grass seed mixture used for reseeding the burns was: — Perennial ryegrass (certified) 101 b. Brown top 21b. Crested dogstail 41b. Danthonia 21b. White clover (certified) .... 21b. Lotus major 11b. Total per acre 211 b. This report is being written after the third year of treatment, and al-

though there may be better results in the years to come, there may also be a decline because of the uncertainty of fertiliser supplies. Detailed Results. Block 1 This block was topdressed with 2cwt. per acre of superphosphate each year in the autumn, and apart from the extra heavy stocking with cattle, no

other treatment was given. The topdressings were applied on March 31, 1939, April 19, 1940, and April 7, 1941. During the first two years, little change was noted, except that patches of fem did not spread. Stock grazed right up to the fern, but made no attempt to worry the patches. Since the third topdressing, however, the cattle have started to worry and trample the patches, but so far have made little impression.

Block 2 This block was burned with a flamethrower and resown with grass seed on March 1, 1939, and 2cwt. of superphosphate was applied annually on .the same dates as in Block 1. At the time of burning the ground was very dry, and a good, clean burn was obtained. The grass seed, although sown on very dry ground, gave a fairly satisfactory establishment, and with the rains later in the season gave good ground cover. At the end of twelve months there was little hard fern to be found on the block, while after three years it is practically impossible to find the old burns. The only hard fern at present on this block is round the top of a slip which broke' away in February, 1940. The hard fern on the pegged plots survived until after the second topdressing and then disappeared, and there has been no sign of any revival. The heavy stocking with cattle was responsible for the disappearance of any fern which survived the fire, and the grass establishment has been good. Block 3 The hard fern on this block was first treated with a mixture of 281 b. of sodium chlorate and scwt. of lime per acre on February 27 and 28, 1939, and on March 8 and 9, 1939, was burned with a flame-thrower and sown with grass seed. Fertiliser was applied on the same dates, and at the same, rate as in Block 1. The ground was dry, and there was more dead and withered fern after the sodium chlorate treatment, and the burn on this block was the cleanest. The strike of grass and establisment was better than the other blocks, but after the second topdressing there appeared to be little difference between

this and grass on Block 2. Hard fern on the pegged plots disappeared in the first year, and there has been no sign of any revival. At the present time this block is carrying a good, even sward, and it is impossible to distinguish the burned patches from the rest of the sward. Block 4 This block was burned with a “firestick” and- resown with grass seed on March 1, 1939. The ground was dry, and a fairly good burn resulted, although a fair amount of fern survived, most of it being in fringes on the lower edges of the patches. Fertiliser was applied as in Blocks 1,2, and 3.

The grass strike was only fair, but there was sufficient established to give a good cover. The cattle did exceptionally good work on this block, and although the burn was not as good as on Blocks 2 and 3, there was little difference between them at the end of twelve months. Practically all the fem disappeared after the second topdressing, and at the present time there is little difference between Blocks 2, 3, and 4. Reports show that the fern persisted longer on the pegged plots than on any of the other autumn-burned areas, but the heavy stocking with cattle completed the destruction . even , on ' this block where the bum was not good. • Block 5 This block was to be burned with a flame-thrower, reseeded, and topdressed in the spring, but the actual burning and topdressing was delayed until November 17, 1939, because of very wet conditions. Whejn burned, the ground was very dry, but there was a fair amount of new growth, and the fires did not carry at all well. Much

time was spent on the fringes and unburned edges, but it was impossible to get a clean burn. The block was sown and topdressed, with a resulting fair strike, and the grass has made quite a fair cover on the burns. Stock neglected this block after the treatment, and it was not until the following winter after the second topdressing of superphosphate on April 17. 1940, that the block was at all well grazed. Because of this neglect all the hard fem which survived, the, fire made good growth, and it was not until the winter of 1940 that the spread was checked with cattle. Bracken fern also appeared in the neglected pasture and made the block more unsightly. In the following spring the block was fairly well grazed, but it was not until the third topdressing that it was as well grazed as the others. The result of this treatment is that the hard fern, although not covering such a large area as previously, is still well established over the whole

area, but is now being held m cnecK. There is no sign of the cattle damaging the remaining patches of fern. The newly-sown grass is not as strong as the grass on the other blocks, and the old pasture has not improved to the same extent as the pasture on the other areas. >. ' ' This treatment has been a failure in comparison with the other burned areas, but if this area had been fenced off from the autumn-treated areas, the results might have been better. Even so, one could not recommend spring burning because of the difficulty in getting suitable weather or a clean burn when the fern is growing. Conclusion From the information given in this experiment and also from observation of farming methods, it is quite evident that hard fern can be eradicated, and that many areas at present occupied by this pest could carry good productive pastures.,. The chief failing of past practice in the control of this pest has been, firstly, the overstocking of pastures with sheep and the understocking with run cattle. : \ . Previously, farmers have either allowed the land to revert through the hard fern stage to bracken fern, and have then burned and reseeded the burn, or have burned the patches of hard fern and given little attention to the regrassing of the scars and the consequent stocking and topdressing. Hard fem can be eradicated, and it would appear that the best method is to burn the patches of fern thoroughly in the autumn, reseed the burns with a suitable grass seed mixture, and follow up with topdressing and good pasture management. The heavy stocking with run cattle is essential for at least the first twelve months to crush out any surviving fem.