These three lines should be identical, but differ (K.J.Symespers. comm.). If Festiguay's resistance was derivedfrom Uruguay 392 then the most likely parent would havebeen AUS 1521, because AUS 1519 was not introduced toAustralia from the USA until 1952 (the year after the crosswas made), and AUS 1533 was in the Sydney Universitycollection. All three lines are susceptible, as is the otherreputed parent cv. Festival.

The variety Festival probably does not figure in thepedigree of Festiguay either. This, according to K.J. Symes(pers. comm.) is "most ironical, because for all its commer­cial life, the variety Festiguay was excluded from the topwheat grade in northern N.S.W. because of a supposedresemblance to Festival!",

It is also known that Festiguay possesses a gene for rustresistance (not present in Festival), which is derived fromcv. Webster. It is unlikely that Webster itself was used as aparent, but one of its derivatives cv. Febweb (Federation XWebster, made in 1926) may have been used. Three linesof Fedweb from the Tamworth collection, and other lines ofFedweb, and Webster from the Australian Wheat Collec­tion also proved susceptible to CCN in my tests.

In view of the disease, quality, and agronomic charactersof Festiguay on the one hand, and the varieties Mathesonwas working with, on the other (K.J. Symes pers. cornrn.),the most likely pedigree might have been Gabo X Fedweb,but Gabo is also susceptible.

It is clear that the parents of Festiguay are not those onwhich registration of the variety was based. The questionmay be asked, "what are they?".

ACKNOWLEDGEMENTSI thank Mr. K.J. Symes, Curator of the Australian Wheat

Collection for his help in providing background andhistorical information on the varieties tested, and forproviding seed. The assistance of Mrs. L. Clarkson in theglasshouse and laboratory is gratefully acknowledged.

* AUS is the prefix to accession numbers in the Australian WheatCollection

REFERENCES

(1) Brown, J.A.M. (1974) - Testtube reproduction of Heteroderaavenae on resistant and susceptible wheats.Nematologiea 20: 192-203.

(2) Brown, JAM. and Ellis, S.E. (1976) - Breeding forresistance to cereal cyst nematode in wheat. Euphytiea 25:73-82.

(3) Brown, R.H. (1974) - Further studies on the Victorian biotypeof the cereal cyst nematode (Heterodera avenae).Australian Journal of Experimental Agriculture and AnimalHusbandry 14: 394-398.

(4) Brown, R.H. (1982) - Studies on the Australian race ofHeterodera avenae. EPPO Bulletin 12: (in press)

(5) Brown, R.H. (1982) - Nematode diseases. In, "Economic im­portance and biology of cereal root diseases in Australia".Report to Plant Health Committee of Standing Committeeon Agriculture.

(6) Brown, R.H. and Meagher, J.W. (1970) - Resistance incereals to the cyst nematode (Heterodera avenae).Australian Journal of Experimental Agriculture and AnimalHusbandry 14: 360-365.

(7) Brown, RH. and Young. RM. (1982) - Katyil, a wheat resis­tant to cereal cyst nematode. Agnote. Department ofAgriculture, Victoria. Agdex 112/38. 2pp.

June 1982 15

(8) Macindoe, S.L. and Walkden Brown, C. (1968) - "Wheatbreeding and varieties in Australia". Science Bulletin No.76, New South Wales Department of Agriculture. 255pp.

(9) Mcleod, R.W. (1976) - Sources of resistance to Heteroderaavenae WolL in New South Wales. Proceedings of the Lin­nean Society of New South Wales 100: 195-201.

(10) Meagher, J.w. (1972) - Cereal cyst nematode (Heteroderaavenae WoIL). Studies on ecology and control in Victoria.Victorian Department of Agriculture, Technical BulletinNo. 24. 50pp.

(11) Meagher, J.w. (1977) - World dissemination of cereal-cystnematode (Heterodera avenae) and its potential as apathogen of wheat. Journal of Nematology 9: 9-15.

(12) Nielsen, C.H. (1966) - Untersuchungen uber die vererbungder Resistenz gegen den Getreidenematoden (Heteroderaavenae) bstm Weitzen. Nematologiea 12: 575-578.

(13) O'Brien, P.C. (1972) - Investigations of resistance in wheat,barley and oats to Heterodera avenae Woli. M. Agr. Sc.Thesis, University of Adelaide 125pp.

Torula Yeast: A Growth Supplement for Im­proving Sporulation of Peronosporahyoscyami on Tobacco

Greg JohnsonDepartment of Primary Industries,

Mareeba, Queensland, 4880

Peronospora hyoscyami de Bary is an obligate parasitecausing the disease blue mould of tobacco. The funguscan be maintained by regular transfer of conidia ontohealthy leaf tissue, or by cryogenic storage (1, 2).

Several times during the last few years at Mareeba,north Queensland, the isolate of P. hyoscyami being main­tained by weekly transfer of fresh conidia in aqueoussuspension has become less vigorous, with little sporula­tion occurring on inoculated plants. Sometimes the culturehas been lost despite the provision of optimal environmen­tal conditions for growth and sporulation.

Shepherd (4) studied conidial germination of P.hyoscyami in vitro. He found that conidia washed by cen­trifugation to remove a germination inhibitor germinatedpoorly or not at all in water alone, but germinated well inthe presence of riboflavin. The addition of other vitaminsdid not influence germination. Germination in vivo was alsoimproved by the addition of riboflavin to inoculum (5).

This work describes studies on the use of Torula yeastas an amendment to conidial suspensions to stimulatesporulation of P. hyoscyami. An isolate of blue mould (P.hyoscyami f. sp. tabacina maintained on tobacco seedlingscv, Hicks Q46 was used in these investigations. Conidialsuspensions were prepared using a method similar to thatof Shepherd (4), and Torula yeast was added to one half ofthe inoculum (5 g/I). Vigorous seedlings were inoculatedusing the spore suspension (5 x 10' conidia/ml) either withor without added yeast. Plants were maintained in a con­trolled environment cabinet (20/25 C day/night, 12 hr days,30-40,000 lux) and incubated in plastic bags after inocula­tion (24 hr) and 6 days later (24 nr), to encourage sporula­tion.

Seven days after inoculation, two leaves bearing fungalgrowth were harvested from each of three plants/treat­ment. The spores were dislodged by gently agitating theleaves in 30 ml water for 60 seconds. Spore concentrationof the suspension was determined by counting 10 fields onan haemocytometer. The total spore yield of the harvested

leaves was calculated as the product of the spore concen­tration/ml and the volume of the spore suspensions (i.e.30ml). The area of the harvested leaves was estimated us­ing a planimeter. Spore production per unit area wascalculated as the quotient of total spore yield/treatmentdivided by the total area of the harvested leaves (both

des).The addition of yeast to inoculum markedly increased

sporulation (Table 1.) In subsequent experiments, the ad­dition of Torula yeast to inoculum has produced similarresults

Table 1. Effect of amendment of Peronospora hyoscyamiinoculum with Torula yeast* on conidial production intobacco seedlings

Spore productlon/crnsInoculumtreatment

7 daysafter inoculation

Amended with Torulayeast 178.8

Unamended 9.4

* Sanitarium Torula yeast. According to the package con­tains 10mg riboflavin/100 g.

Shepherd and Mandryk (5) found that the requirementfor maximum percentage germination in vivo was 20 griboflavin/m! or !ess depending on the riboflavin content ofthe leaf. They cited preliminary experiments indicating thatthe concentration of riboflavin in leaves varied con­siderably when plants were grown at different times of theyear and under different conditions.

Some work on the nutrition of P. hyoscyami wasreported by Mandryk (3). He listed seven vitamins(including riboflavin) and five purines and pyramidineswhich stimulated sporulation when leaf discs in the pre­sporulation phase were floated on solutions containing thetest materials.

Inoculum prepared as described here contained 500/J. g riboflavin/ml, more than adequate for maximum ger­

mination. Torula yeast is an excellent source of many of thecompounds listed by Mandryk (3) as promoting sporula­tion. Its addition to the inoculum probably ensured that thenutritional requirements for P. hyoscyami after germina­tion were also satisfied, resulting in the improved sporula­tion observed. Torula yeast has been routinely incor­porated in blue mould inoculum since February, 1981 andcultures have been vigorous, producing abundant sporula­tion 6-7 days after inoculation.

When fungicidal efficacy or variations in host resistanceare being studied experimentally using washed conidial in­oculum, nutritional conditions for the growth and sporula­tion of P. hyoscyami should be optimal. The addition ofTorula yeast to the inoculum would appear to satisfy thisrequirement.

ACKNOWLEDGEMENT

This work was supported by funds from the AustralianTobacco Industry.

REFERENCES

(1) Bromfield, K.R. and Schmit,e.G. (1967 - Cryogenicstorageofconidia of Peronospora tabacina. Phytopathology 57:1133.

(2) Cohen, Y. and Kuc, J. (1980) - Infectivity of conidia ofPeronospora tabacina after freezing and thawing. PlantDisease 64: 549-550.

16

(3) Mandryk, M. (1962) - The effect of various compounds onsporulation of Peronospora tabacinia Adam in vitro.C.S.I.A.O. Australia, Division of Plant Industry AnnualReport 1961-62. Canberra.

(4) Shepherd, C.J. (1962) - Germination of conidia ofPeronospora tabacinia Adam.. I. Germination in vitro.Australian Journal of Biological Sciences 15: 483-508.

(5) Shepherd, C.J. and Mandryk, M. (1963) - Germination of con­idia of Peronospora tabacina Adam. II. Germination invivo. Australian Journal of Biological Sciences 16: 77-87.

NEW DISEASES

Red Rust (Cepha/euros virescens) on Teain Queensland

G.1. Johnson and F.R. Hobman,Queensland Department of Primary Industries,

Mareeba, 4880

Commercial tea (Camellia sinensis (L.) Kuntze) growingcommenced in Queensland during the 1950's (3).Establishment was slowed due to the need for mechanicalharvesting equipment, but since the opening of a tea tac­tory in 1970, a viable industry has gradually developed.During 1981, 370,000 kg of tea worth $700,000 wereproduced from 160 ha, So far, disease problems havebeen minor (4).

During November 1980, several moribund tea busheswere noticed amongst vigorously growing seventeen-year­old hedges at Nerada tea estate near lnnlstall, northQueensland. Portions of the branches from one and twoyear old growth on these bushes were covered by a super­ficial reddish pubescence. These symptoms resembledliterature descriptions of "red rust" caused by the algaCephaleuros. Microscopic examination revealed that theaffected areas of the stems were profusely covered withfruiting bodies borne on short stalks and these were iden­tified as Cephaleuros virescens Kunze.

Red rust is regarded as a troublesome disease of teawhich when uncontrolled can debilitate plants and reduceproductivity. Strategically timed copper sprays arereported to give satisfactory control (2, 5).

Although C. virescens has been recorded on other hostsin Australia (1) this appears to be the first record on tea. Aspecimen of the disease has been lodged in the herbariumof the Plant Pathology Branch, Queensland Department ofPrimary Industries (BRIP 13252).

ACKNOWLEDGEMENTS

Dr. A.B. Cribb of the Botany Department, University ofQueensland, identified the algal specimen.

REFERENCES

(1) Bailey, F.M. (1913) - Comprehe~sive Catalogue ofQueensland Plants. Government Printer: Brisbane.

(2) Hainsworth, E. (1952) - Tea pests and diseases and their con­trol. Hefler and Sons: Cambridge.

(3) Hobman, F.R. (1973) - TeaGrowing.Queensland AgriculturalJournal 99: 226-233.

(4) Hobman, F.r. (1980) - Tea in Queensland. QueenslandAgricultural Journal 103: 386-407.

(5) Joubert, J.J. and Rijkenberg, F.H.J. (1971) - Parasitic algae.Annual Review of Phytopathology 9:: 45-64

Australasian Plant Pathology