temperature of 32 C for the development optimize conditions for infection and to Research Institute, Department of Agriculture,of bitter rot in the field (1,4). complete the secondary cycle. New South Wales. Agric. Gaz. N.S.W., December,

Infection, as measured by percent of An apple with one bitter rot lesion 1970. pp. 647-650.3. BROOK, P. J. 1977. Glomerella cingulata and

apples infected and lesions per infected would not be marketable. Because more bitter rot of apples. N.Z. J. Agric. Res. 20:547-555.

apple, was favored at 26 C. However, 12 than two-thirds of the apples inoculated 4. DRAKE, C. R., K. D. HICKEY, and G. M.

days after inoculation, lesion area was at 22, 26, and 28 C were infected, there SHEAR. 1970. Apple diseases and their control in

greater at 30 C. This rapid expansion is would be little difference in the economic Virginia. Va. Polytech. Inst. Coop. Ext. Serv.Publ. 374.

important in terms of the secondary losses at these temperatures. However, 5. EDGERTON, C. W. 1915. Effect of temperature

spread of the pathogen, which is accom- the more rapid development of lesions at on Glomerella. Phytopathology 5:247-259.

plished by means of conidia (Col- the higher temperatures would enhance 6. HOPPERSTEAD, S.L.,M.W. GOODWIN, andletotrichum gloeosporioides Von Arx.) secondary spread of inoculum and K. J. KADOW. 1943. Bitter rot of apples and its

control in Delaware. Agric. Exp. Stn., Univ.

produced in acervuli on the surface of provide more rapid disease development. Del. Bull. 241.

lesions (1,4). Lesions produced at higher 7. McGLOHON, N. E. 1978. Apple spray guide for

temperatures would produce a more LITERATURE CITED middle Georgia. Coop. Ext. Serv., Univ. Ga.

abundant source of inoculum. Cooler 1. ANONYMOUS. 1956. Diseases of apples and Bull.740.pears. Univ. Ill. Coop. Ext. Serv. Publ. 16. 8. TAYLOR, J., and N. E. McGLOHON. 1975.

temperatures, such as may be expected 2. ANONYMOUS. 1970. Bitter rot of apples. Apple diseases and their control. Ga. Agric. Res.

during rainfall, would be necessary to Biology Branch, Biological and Chemical Spring 1975. pp. 8-1 1.

Field Resistance of Pea Germ Plasm to Powdery Mildew (Erysiphe polygoni)and Rust (Uromycesfabae)

A. B. PAL, Vegetable Breeder, and BRAHMAPPA, Scientist-S, Department of Vegetable Crops, and R. D. RAWALand B. A. ULLASA, Scientists S-l, Department of Plant Pathology, Indian Institute of Horticultural Research,Bangalore-560 080, India

ABSTRACTPAL, A. B., BRAHMAPPA, R. D. RAWAL, and B. A. ULLASA. 1980. Field resistance of pea Three accessions- PJ207508,germ plasm to powdery mildew (Erysiphepolygoni ) and rust (Uromycesfabae). Plant Disease 64: PJ222117, and EC 109188-were resistant1085-1086. to rust. All the rest were susceptible or

highly susceptible to rust. Only PJ207508Atotalof292 accessionsofpea(Pisumspp.)werescreenedunderfieldconditionsforresistanceto was resistant to both diseases.powdery mildew (Erysiphepolygoni) andrust (Uromycesfabae). Five entries-P43 1, P436, Gloire The accessions found resistant to rustde Quimper, Sel. 18, and Sel. 30-one wild type (PJ207508), and the species Pisum asiaticum were are not recommended for commercialresistant to powdery mildew. Three accessions--PJ207508, PJ222117, and EC109188-wereresistant to rust. PJ207508 was resistant to both diseases. cultivation but could be used by breeder

to produce cultivars resistant to bothdiseases. None of the pea cultivars tested

Powdery mildew (Erysiphe polygoni spores in water (20-25 spores per by Prasada and Singh (4) in Rajasthan

DC.) and rust(Uromycesfabae(Pers.)de microscopic field at X10) collected from showed any resistance to rust. Golubev

Bary) limit pea (Pisum sativum L.) infected plants. Powdery mildew and Kornevr(1) reported resistance to i

production in various parts of India inoculations were made 1 wk later by pisi (Pers.) Wint. (not prevalent in IndiU

(2,4,5). Both diseases are widespread and dusting plots with freshly harvested in some fodder peas from the USSR, bt

cause severe losses in south India. inoculum. no resistance to U. fabae has been

Although breeding programs are in Disease incidence was recorded reported.

progress, none of the commercial periodically until crop maturity. Cultivars Munjal et al (2) observed 21-31%cultivars-available in India are resistant were categorized as resistant (no reduction in p wet i An c O P7%

to either disease. Effective, economical pustules), moderately resistant (less than inedctedn bn owdwer gh midw Srohi et0a0control of rust with fungicides is not 5% of foliage area infected), moderately ifceby podr y mle.Sh ta 5

posibl. e srenedaccssonsof susceptible (6-25% infected), susceptible reported some cultivars moderatelypossble We crened ccesion ofresistant to powdery mildew and rust, butPisum spp. collected from all over the (26-50% infected), and highly susceptible none that were completely resistant.

world to locate sources of resistance to (more than 51% infected). Pierce (3) found a selection from thethese diseases for use in breedingprograms. RESULTS AND DISCUSSION cultivar Stratagem that was immune to

Five entries--P431, P436, Gloire de powdery mildew and transferred thischaracter to several commercial cultivars.MATERIALS AND METHODS Quimper, Sel. 18, and Sel. 30--and two Thliefonrsstttoihrorbh

Altogether, 269 entries and 23 species other species--P. asiaticum and PJ207508 Thliefonrsstttoihrorbhof Pi'sum were sown in 1976 and 1977 10 (an unidentified wild species)--were of these diseases are being used in thecm apart in 4.5-in rows with 30 cm classified as resistant to powdery mildew. breeding program at the Indian Institute

between rows. The plants were inoculated Nine entries--Olympia-I, Weitor, o otclua eerhafter 20 days with a suspension of rust BC 108208, P. puschki, L-l1584, P. LTRTR IE

humile, P. elatius L-5232, AC 12092, and 1. GOLUBEV, A. A., and A. I. KORNEV. 1975.Contribution 897 of the Indian Institute of Erygel--were moderately resistant to Immunological study of initial material forHorticultural Research. Project 2.1.12. powdery mildew, and two entries-- breeding Pisum. P1. Br. Abstr. 46:6345.

Tridn an P43--wre mderaely 2. MUNJAL, R. L., V. V. CHENULU, and T. S.Trion nd 439wer moeraely HORA. 1963. Assessment of losses due to

0191-2917/80/12108502/$03.00/0 susceptible. The rest were susceptible or powdery mildew Erysiphe polygoni DC. on pea.@1980 American Phytopathological Society highly susceptible to powdery mildew. Indian Phytopathol. 16:260-267.

Plant Disease/December 1980 1085