H.—34

(b) Carrot Rust-fly. —Work has been continued on the seasonal cycle and has confirmed previous findings that there are three main emergence periods in the year —namely, September-October, end of December, and end of February. A fourth probably occurs towards the end of April. (c.) Vegetable-weevil. —The life-cycle and seasonal-cycle of this pest has been worked out, and results are now ready for publication. (d) Pittosporum psyllid. —Similar work has been completed on this pest, which attacks hedges of Pittosporum. Results are ready for publication. (e) Stored-grain Pests. —At the request of British authorities, tests were made of inert dust developed in England to protect stored grain from weevil attack. Although chemically inert, such dusts kill by promoting evaporation of moisture from the insect body. Tests were made of its effects on bean and wheat weevils at concentrations of 1 part to 1,800 parts of beans and 1-1,000 of wheat. The dust proved most effectual; but it is considered unnecessary to employ such a product, since a Dominion-wide survey showed that in general stored grain suffers so little damage from insect attacks that costs of incorporating the dust are not warranted. (/) Citrus-canker.—A further outbreak occurred in Tauranga, necessitating destruction of infected citrus trees in an area where eradication measures have not been forced. It is now three years since the last outbreak was reported from Kerikeri, showing that adequate control of this serious disease can be secured by eradication of infected orchards. (g) Linen-flax Diseases.—A survey of South Canterbury areas was made early in 1945. The only disease noted was rust, which was prevalent in some late-sown crops. Specimens from Otautau infected with true browning were sent in from one commercial crop. Infection was confined to a few scattered etiolated areas in the crop. (h) Eye-spot of Wheat. —Following a rapid survey in North and Mid-Canterbury, this disease was found only in Lincoln, these confined to a few plants in a small experimental plot at the farm of the Wheat Research Institute. (i) Vegetable Diseases. —A co-ordinated scheme for control of diseases in Services' vegetableproduction areas under control of the Department of Agriculture was worked out during the winter of 1944. One week of intensive training was given at the Division's headquarters to eighteen men in charge of these areas. (j) New Pests and Diseases. —A serious pest of vegetable crops overseas, Nezara viridula, was collected at New Plymouth last April. Larva 3 of one of the white-fringed beetles, possibly Pantomorus leucoloma, was found in Hastings attacking roots of ornamental plants. The beetle is a pest of economic crops overseas. A serious overseas rust of raspberry, Phragmidium rubi-idaei, was collected in Palmerston North last year and has since become widespread in that locality. (k) Tomato-streak. —Infected specimens were forwarded from Hutt Valley, Wanganui, and Cheviot, in which localities the disease has caused heavy losses. Inoculations with the pure virus have shown the disease to be identical with Lycopersicum Virus I of Smith 1937. (I) Yellow-leaf of Phormium tenax. —Preliminary investigations into the cause of this disease have been initiated. A brief survey of Moutoa area, in the Manawatu, has shown that incidence varies from a trace to as high as 85 per cent. Some varieties of flax would appear to be more susceptible than others, but none is immune. (m) Fruit-tree and Small-fruit Diseases. —See Fruit Research Report, p. 16. 11. Therapeutant Testing (See also Fruit Research report, p. 16.) Soil Treatments.—Further investigations have been carried out with use of chloropicrin. This chemical controls soil nematodes, damping-off fungi, and verticillium-wilt. Commercial methods have been devised for treating soils. Trials have been extended to tomato glasshouse soils and have shown that marked improvement in yield follows control of nematodes. A new product, D.D. (a mixture of dichloropropane and dichloropropylene), has given results comparable with chloropicrin. D.D. is cheaper and less objectionable to use, so should prove of considerable value when available in commercial quantities. Several cases of injury to Canterbury tomato crops were reported consequent on growers using as a soil treatment commercial formaldehyde which had deteriorated in the containers with formation of paraformaldehyde. Not only did such a product fail to control verticillium-wilt, but also caused injury to young plants. 111. Timber Preservation (See Timber Protection report, p. 6.) IV. Pomology Investigations (See Fruit Research report, p. 16.) V. Miscellaneous (a) Lucerne Culture.—Cultures have been supplied to 1,400 farmers sufficient to inoculate 188,700 lb. of lucerne seed, an increase of 19,2001b. over 'last season's supply and nearly 40,0001b. over that of 1942-43 season. (b) Rot-proofing of Fabrics.- A large series of investigations has been completed and a suitable technique evolved for testing various chemicals used to protect canvas fabric against decay caused by fungi and bacteria, and effects of weathering upon them. The process has also been employed to test effects of chemicals used to proof cotton and linen thread used in canvas and boot manufacture and cordage used in shipping, &c. (c) Control of Flies and Cockroaches.—Effects of D.D.T. in control of flies in meat-works was investigated in the North Island. A team of American servicemen from the Pacific war zone carried out work of applying the product, and the Division has made periodic inspections of results. Promising control has been secured, D.D.T. after one application being still effectual after a time interval of two months.

5—H. 34.

33