Journal of the Department of Agriculture, Western Australia, Series 4

Volume 7 Number 4 1966 Article 6

1-1-1966

Septoria leaf spot and glume blotch of

W A. Shipton

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Recommended Citation Shipton, W A. (1966) "Septoria leaf spot and glume blotch of wheat," Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 7 : No. 4 , Article 6. Available at: https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol7/iss4/6

This article is brought to you for free and open access by Research Library. It has been accepted for inclusion in Journal of the Department of Agriculture, Western Australia, Series 4 by an authorized administrator of Research Library. For more information, please contact [email protected], [email protected], [email protected]. PLANT DISEASES

SEPTORIA LEAF SPOT AND GLUME BLOTCH OF WHEAT

By W. A. SHIPTON, Ph.D., Plant Pathologist

SEPTORIA leaf spot and glume blotch of wheat occur throughout Australia and are cap­ able of reducing crop yields. While no estimates of yield losses are yet available in Western Australia both diseases can cause serious damage to crops.

Septoria leaf spot is caused by the fun­ Environmental Conditions Favouring the gus Septoria tritici Rob. ex Desm. and Disease glume blotch by the related Septoria Infection may take place over a wide nodorum Berk. range of temperatures. The disease is Glume blotch and Septoria leaf spot usually conspicuous in cool to mild, wet were first recorded in Western Australia conditions, but may occur in warmer in 1905 and 1924 respectively (Sutton, 1920; weather provided that there is sufficient Carne and Campbell, 1924), and now occur moisture for infection. in all the wheat growing districts of the State. In many overseas countries the Carry-over From Crop to Crop diseases have been reported to cause con­ The organism persists during the dry siderable losses, yet few precise estimates months of the year in infected plant debris have been made of these. In Indiana and (Hilu, 1956). In the autumn, spores are New Zealand losses in yield of 24.3 and released from the moist and are dis­ 9.7 per cent, were recorded from natural persed by wind and rain splash. These infections of Septoria leaf spot (Caldwell spores infect susceptible hosts. In Western and Narvaes, 1960; Sanderson, 1964). No Australia the organism has only been iso­ precise estimates of losses due to glume lated from wheat; overseas it has been blotch are available, but total crop failure found on other hosts (Sprague, 1950). has been reported. Susceptibility of Wheat Varieties Septoria Leaf Spot Wide variations have been noted in the The organism causing leaf spot is also susceptibility of wheat varieties to Sep­ capable of infecting the leaf sheaths. toria leaf spot. Critical observations have Symptoms been carried out for a number of years The first sign of infection is the appear­ at various localities, and the wheat variety ance of light green to yellowish green spots Kondut has consistently shown a degree between the veins of the leaf or leaf of resistance. The wheat variety Festi- sheath. The pathogen spreads rapidly guay also appears to have some useful re­ through the host tissue causing the devel­ sistance. opment of light brown to light yellow irre­ gular areas on the leaf and leaf sheath Glume Blotch respectively (Fig. 1A). Eventually the dis­ The glume blotch organism is not re­ coloured areas assume a speckled appear­ stricted to infection of the floral bracts. ance due to the formation of fruiting Infection of all the aerial parts of the bodies or pycnidia (Fig. IB). plant may occur. 160

Journal of Agriculture, Vol 7 No 4 1966 SEPTORIA LEAF SPOT

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FIG. 1.—A. Wheat leaves and sheaths infected by Septcria tritici. B. Fruiting bodies or pycnidia of S. tritici on wheat leaves.

GLUME BLOTCH

FIG. 2.—Septoria nodorum on the leaves, sheaths, nodes, peduncles, and the glumes of wheat.

161 12) 24857

Journal of Agriculture, Vol 7 No 4 1966 FIG. 3.— A comparison of normal grain with small and shrivelled grain resulting from infection of Eureka wheat with both S. nodorum and 5. tritici.

Symptoms Carry-over from Crop to Crop The lesions caused by the organism are As with Septoria leaf spot, the glume often conspicuous on the floral bracts, but blotch organism persists from crop to crop may also be conspicuous on other parts in the infected plant debris. Spores are of the plant (Fig. 2). released from the infected straw when it The lesions are at first small, linear to has been moist for a sufficient time, and oblong, and light green to yellowish green. are dispersed by wind and rain splash As the fungus spreads through the host (Scharen, 1964). In Western Australia the tissues the lesions change to dark brown disease has been found on wheat and the or purplish brown and on the nodes they commonly occurring "ripgut" brome grass may carry a bloom. They may spread and (Bromus gussonii Pari.). Overseas it has been found on a large number of grass coelesce so that much of the host tissue v becomes discoloured. Late in the season hosts (Sprague, 1950). the floral bracts often assume a speckled appearance due to the formation of Susceptibility of Wheat Varieties pycnidia. In other countries it has been shown The fungus is capable of causing light that there is a wide range in the sus­ to dark brown spots on the grain, par­ ceptibility of wheat varieties to the disease. ticularly at the embryo end. However, not Observations made to date in Western all grain discoloration is caused by S. Australia have failed to show differences nodorum, and the symptoms caused by in the susceptibility of commercial wheat other fungi are, in general, indistinguish­ varieties to the disease. The position is able from those caused by the glume complicated by the possibility that differ­ blotch organism. ent strains of the organism may exist here as has been demonstrated eleswhere (Thomas, 1962). Environmental Conditions Favouring the Disease Infection and development of the organ­ Losses ism is favoured by ample moisture and No exact estimates of yield losses are as mild conditions. The severity of the attack yet available for Western Australia. How­ varies with the date of onset of infection, ever, it is known that in cases of severe early infection leading to heavy losses infection by both diseases the crop may (Pirson, 1960). In Western Australia, late not be worth harvesting for grain. maturing crops are less liable to glume The yield losses associated with infec­ and grain infection because of the drier tion by S. nodorum are generally caused conditions at heading. by shrivelling and weight loss of grain

Journal of Agriculture, Vol 7 No 4 1966 (Bockmann, 1962). Seed-borne infection 2. Burhardt, Z. I. (1954). [Septoria nodorum may damage the emerging shoot, chiefly Berk, on tillering spring wheat.] Trud. vsesoyuz. Inst. Zashch. Rast., 5: 120-130. the coleoptile, which may result in de­ Abstracted in Rev. appl. Mycol., 37:33. creased plant vigour (Kietreiber, 1961; Noble, 1956). 3. Caldwell R. M., and Narvaes, I. (1960). Losses to from infection by Septoria leaf spot has been shown to Septoria tritici. Phytopathology, 50:630. lead to a delay in grain maturity, to yield and bushel weight losses, and to of 4. Carne, W. M., and Campbell, J. G. C. (1924). Mildew, Septoria, leaf spots and similar inferior quality (Chester, 1945). diseases of cereals. Bull. 121, Dept. Agric. Fig. 3 shows the poorly-developed and W. Aust., pp. 6. shrivelled grain which resulted from a 5. Chester, K. S. (1945). Defoliation and crop heavy infection of both diseases on early losses. Plant Dis. Reptr, 29: 162-168. sown wheat at Beverley in 1964. 6. Hilu, H. M. (1956). Inoculation, life cycle Control and host-parasite relationship of Sep­ toria tritici Rob. on Triticum species. Diss. Control of these diseases is difficult but Abstr., 26:1550. their incidence can be minimized by the 7. Kietreiber, M. (1961). [The diagnosis of following measures. Septoria infection of wheat grains by • Treat the seed with an organic seed testing.] PflSchBer., 26:9-10. Ab­ mercury dust. This will control stracted in Rev. appl. Mycol., 42:87-88. the seed-borne phase of S. nodorum 8. Noble, M. (1956). Cereal seed health. Re­ (Burhardt, 1954; Ponchet and sults of a laboratory seed survey. Scot. Auge, 1959). Agric, 36:86-90. 9. Pirson, H. (1960). [Testing of different • Dispose of crop residues either by winter wheat varieties for susceptibility burning or deep ploughing. to Septoria nodorum Berk, using artificial • When practicable, grow wheat on infections.] Phytopath. Z., 37:330-342. land well separated from paddocks Abstracted in Rev. appl. Mycol., 39:466. cropped to the cereal during the 10. Ponchet, J., and Auge, G. (1959). [At­ tempts at control of damping-off of previous seaon. cereal seedlings.] Phytiatrie-Phytopharm., • Plant the wheat varieties recom­ 8:141-149. Abstracted in Rev. appl. mended for the district at the cor­ Mycol., 39:466. rect time, and feed-off crops which 11. Sanderson, F. R. (1964). Effect of leaf are forward. spot (Septoria tritici) in autumn-sown wheat crops. N.Z. Wheat Rev., No. 9 • Use resistant varieties when they (1962-1964) pp. 56-59. are available. Only provisional re­ 12. Scharen, A. L. (1964). Environmental in­ commendations can be made at fluences on development of glume blotch present. The wheat varieties Kon- in wheat. Phytopathology, 54:300-303. dut, and, to some extent, Festiguay, 13. Sprague, R. (1950). Diseases of Cereals and have shown resistance to Septoria Grasses in North America. New York: leaf spot. The Ronald Press Co., pp. xvi 4- 538. 14. Sutton, G. L. (1920). Take-all, Septoria, REFERENCES rust and wheat mildew. Practical 1. Bockman. H. (1962). [Artificial inoculation methods of control. Bull. 69, Dept. Agric. tests with Septoria and Fusarium on W. Aust., pp. 27. various winter wheat varieties in the 15. Thomas, M. H. (1962). Factors affecting Northeast Polder in summer 1961.] Tech. glume blotch development of wheat and Ber., ned. Graan—centrum, 8:1-23. Ab­ variation in the casual organism, Sep­ stracted in Rev. appl. Mycol., 42: 189-190. toria nodorum. Diss. Abstr., 23:789.

163 (3) 24*57

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Journal of Agriculture, Vol 7 No 4 1966