Selection for resistance to Phytophthora megasperma var. sojae in Hunter River lucerne

1978 ◽  
Vol 18 (94) ◽  
pp. 708 ◽  
Author(s):  
RA Bray ◽  
JAG Irwin
Keyword(s):  
Medicago Sativa ◽  
Root Rot ◽  
Dry Matter ◽  
Dry Matter Yield ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Laboratory Conditions ◽  
Two Generations ◽  
Selection For

Seedlings of lucerne (Medicago sativa) resistant to Phytophthora root rot were isolated from cv. Hunter River by two generations of selection under laboratory conditions. Screening of three-month-old seedlings confirmed the resistance of the selected populations. In the field, when compared with cv. Hunter River, the best population had greater survival, more resistant plants, and twice the dry matter yield.

Lack of control of phytophthora root in lucerne (Medicago sativa) by foliar applications of phosphorus

1991 ◽  
Vol 31 (4) ◽  
pp. 503
Author(s):  
KF Lowe ◽  
MJ Ryley ◽  
TM Bowdler
Keyword(s):  
High Risk ◽  
Medicago Sativa ◽  
Root Rot ◽  
Dry Matter ◽  
Small Reduction ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Resistant Cultivars ◽  
Matter Production ◽  
Lack Of Control

Application of phosphonate was investigated as a means of controlling phytophthora root rot (Phytophthora megasperma f. sp. medicaginis) in lucerne (Medicago sativa). Foliar sprays of the chemical at rates of 2, 4 and 8 g/L did not improve the persistence or dry matter production of susceptible or resistant cultivars of lucerne, despite a small reduction in the degree of damage inflicted on lucerne plants by a severe epiphytotic of the disease. Regular monthly applications gave no better control than single applications at establishment or at the time of the development of an epiphytotic. It is concluded that phosphonate is not efficacious in controlling phytophthora root rot in lucerne and will not improve the performance of susceptible cultivars in high risk situations.

Reaction of lucerne cultivars to Phytophthora megasperma, the cause of a root rot in Queensland

1974 ◽  
Vol 14 (69) ◽  
pp. 561 ◽  
Author(s):  
JAG Irwin
Keyword(s):  
Medicago Sativa ◽  
Root Rot ◽  
Controlled Environment ◽  
Field Site ◽  
Causal Organism ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Disease Surveys ◽  
Infested Field ◽  
Experimental Strains

The causal organism of Phytophthora root rot of lucerne (Medicago sativa) in Queensland was identified as Phytophthora megasperma var. sojae and a brief description of the organism is included. The results of disease surveys show that Phytophthora root rot is widespread and causes serious losses in lucerne in south eastern Queensland. A collection of lucerne cultivars and strains was screened for resistance to P. megasperma var. sojae both in controlled environment chambers and in a naturally infested field site. The cultivar Lahontan and the experimental strains ESI, BDSI, ECRSI and Combined showed high levels of resistance in both situations.

Recurrent selection for resistance to Stemphylium vesicarium within the lucerne cultivars Trifecta and Sequel

1989 ◽  
Vol 29 (2) ◽  
pp. 189 ◽  
Author(s):  
RA Bray ◽  
JAG Irwin
Keyword(s):  
Leaf Spot ◽  
Root Rot ◽  
Recurrent Selection ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Stemphylium Vesicarium ◽  
Colletotrichum Trifolii ◽  
Resistant Lines ◽  
Selection For

Two cycles of recurrent selection for resistance to Stemphylium leaf spot (caused by Stemphylium vesicarium) based on half-sib family performance were made within the lucerne cultivars Trifecta and Sequel. Within Trifecta, 1 generation of selection was sufficient to increase the level of resistance to that of UC 1249 (resistant check), while 2 generations were necessary to obtain equivalent levels of resistance in Sequel. The Stemphylium resistant lines maintained adequate levels of resistance to anthracnose (caused by Colletotrichum trifolii) and Phytophthora root rot (caused by Phytophthora megasperma f. sp. medicaginis) on the basis of glasshouse tests.

Diurnal Variation in Alfalfa ( Medicago sativa L.) Dry Matter Yield and Overnight Losses in Harvested Alfalfa Forage 1

1973 ◽  
Vol 65 (3) ◽  
pp. 413-417 ◽  
Author(s):  
W. R. Knapp ◽  
D. A. Holt ◽  
V. L. Lechtenberg ◽  
L. R. Vough
Keyword(s):  
Diurnal Variation ◽  
Medicago Sativa ◽  
Dry Matter ◽  
Dry Matter Yield ◽  
Medicago Sativa L

EVALUATION OF ALFALFA CULTIVARS FOR REACTION TO CROWN AND ROOT ROT

1985 ◽  
Vol 65 (1) ◽  
pp. 95-98 ◽  
Author(s):  
R. MICHAUD ◽  
C. RICHARD
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Dry Matter ◽  
Forage Yield ◽  
Dry Matter Yield ◽  
Crown And Root Rot ◽  
Disease Free

Fourteen alfalfa cultivars were grown for 2 yr at three locations and evaluated for forage dry matter yield and crown and root rot. Significant differences were found among cultivars for dry matter yield. All cultivars were affected by crown and root rot, most cultivars showing between 20 and 30% of infected tissues. Differences were observed among as well as within the cultivars for disease severity. The frequency of disease-free plants was less than 1.3% of the plants evaluated. Correlation between root rot index and forage yield was −0.87 [Formula: see text] when data were pooled over years and locations.Key words: Lucerne, root rot, cultivar, yield

Factors contributing to poor lucerne persistence in southern Queensland

1977 ◽  
Vol 17 (89) ◽  
pp. 998 ◽  
Author(s):  
JAG Irwin
Keyword(s):  
Bacterial Wilt ◽  
Root Rot ◽  
Crown Rot ◽  
Wide Spread ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Colletotrichum Trifolii ◽  
Disease Survey ◽  
Disease Surveys ◽  
Made In

Lucerne disease surveys made in southern Queensland have shown the presence of seven fungal root and crown diseases. The two most wide spread and serious diseases are Phytophthora root rot (Phytophthora megasperma) and Colletotrichum crown rot (Colletotrichum trifolii). The general disease survey did not reveal the presence of bacterial wilt (Corynebacterium insidiosum) in Queensland. Studies made on the survival of lucerne populations for 2.5 years at three sites in Queensland have shown that disease was the major cause of all detected plant deaths.

Indirect selection for total digestible dry matter yield in forage maize, using stem diameter

1999 ◽  
pp. 367-374
Author(s):  
F. Casañas ◽  
L. Bosch ◽  
E. Sánchez ◽  
A. Almirall ◽  
F. Nuez
Keyword(s):  
Dry Matter ◽  
Indirect Selection ◽  
Stem Diameter ◽  
Dry Matter Yield ◽  
Forage Maize ◽  
Selection For

AC Caribou alfalfa

1992 ◽  
Vol 72 (3) ◽  
pp. 845-847
Author(s):  
R. Michaud ◽  
C. Richard
Keyword(s):  
Medicago Sativa ◽  
Research Station ◽  
Clavibacter Michiganensis ◽  
Maritime Provinces ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Clavibacter Michiganensis Subsp ◽  
Cultivar Description ◽  
Medicago Sativa L ◽  
Moderately Resistant

AC Caribou alfalfa (Medicago sativa L.) is a cultivar developed by the Agriculture Canada Research Station in Sainte-Foy. It is similar to Iroquois in maturity, rate of growth, and fall dormancy. It is highly resistant to bacterial wilt (caused by Clavibacter michiganensis subsp. insidiosus (McCulloch) Davis, Gillaspie, Vidaver & Harris), resistant to verticillium wilt (caused by Verticillium albo-atrum Reinke & Berth.), and moderately resistant to phytophthora root rot (caused by Phytophthora megasperma Dreschs. f. sp. medicaginis T. Kuan & D. C. Erwin). AC Caribou, an alfalfa with fine leafy stems, is well suited for production in Quebec and the Maritime Provinces where winter survival may be a problem.Key words: Alfalfa, Medicago sativa, cultivar description

Selection for resistance to Colletotrichum trifolii in the lucerne cultivars Hunter River and Siro Peruvian

1980 ◽  
Vol 20 (105) ◽  
pp. 447 ◽  
Author(s):  
JAG Irwin ◽  
DL Lloyd ◽  
RA Bray ◽  
PW Langdon
Keyword(s):  
Dry Matter ◽  
Plant Mortality ◽  
River Population ◽  
Colletotrichum Trifolii ◽  
F2 Population ◽  
Two Generations ◽  
Second Year ◽  
Selection For ◽  
Glasshouse Screening ◽  
Made In

Seedlings of lucerne (Medicago sativa) with increased resistance to anthracnose caused by Colletotrichum trifolii, were obtained from cvv. Hunter River and Siro Peruvian by selection through two generations under laboratory conditions. Glasshouse screening of half sib F1 and F2 families confirmed that rapid progress was made in increasing the level of resistance in both populations. In the field, after two years, F1 derivatives had lower percentages of plant mortality and disease indices than their parent cultivars, and F2 derivatives had lower values than their F1 parents. The F2 population of Siro Peruvian, in the second year, yielded 55% and 45% more dry matter than the unselected populations of Siro Peruvian and Hunter River respectively. However, the level of resistance in the field of the Siro Peruvian F2 population was only the equivalent of the unselected Hunter River population, and was inferior to the F1 and F2 populations of Hunter River.

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