Observations on the Seasonal Development of the Grass Heteropogon contortus Infected by the Smut Sorosporium caledonicum

1975 ◽  
Vol 23 (1) ◽  
pp. 45 ◽  
Author(s):  
RA Fullerton
Keyword(s):  
Seasonal Development ◽  
Relative Importance ◽  
Heteropogon Contortus ◽  
Growing Seasons

The tillering behaviour of tussocks of Heteropogon contortus infected by Sorosporiwm caledonicum has been observed over three consecutive growing seasons. It has been established that infected tussocks may bear both smutted and flowering tillers in the course of a season. Some of the flowering tillers contain smut mycelium and are a source of smutted tillers in the following season. The relative importance of the various kinds of tiller to the longevity of the host and parasite is discussed.

Pasture management in semi-arid tropical woodlands: dynamics of perennial grasses

2007 ◽  
Vol 29 (1) ◽  
pp. 87 ◽  
Author(s):  
John G. McIvor
Keyword(s):  
Perennial Grasses ◽  
Individual Species ◽  
Stocking Rate ◽  
Pasture Management ◽  
Management Options ◽  
Exotic Grasses ◽  
Heteropogon Contortus ◽  
Basal Cover ◽  
Growing Seasons ◽  
North East

The effects of a range of pasture management options (introduced legumes and grasses, superphosphate, timber treatment, cultivation before sowing and stocking rate) on the basal cover of perennial grasses were measured from 1982 to 1991 at two sites, ‘Hillgrove’ and ‘Cardigan’, near Charters Towers, in north-east Queensland. Colonisation and survival of eight native and exotic grasses were followed in permanent quadrats in a subset of treatments. Overall, there were significant changes in total basal cover of plots between years and with tree killing, but no significant differences in sown pastures, fertiliser or stocking rate. Basal cover increased when defoliation levels were less than 40% but increases were smaller at higher levels of defoliation and basal cover often declined when defoliation was greater than 60%. Basal cover declined when growing seasons were <10 weeks, remained static with 10–15 weeks growth, and increased when growing seasons were 16 weeks or longer. There was some colonisation in all years but large differences between years. The differences in colonisation between systems were generally small but there was a general trend for higher colonisation at higher stocking rates. Bothriochloa ewartiana (Domin) C.E.Hubb. and Chrysopogon fallax S.T.Blake had low, Heteropogon contortus (L.) P.Beauv. ex Roem.&Schult., Cenchrus ciliaris L. and Aristida spp. had intermediate, and Bothriochloa pertusa (L.) A.Camus and Urochloa mosambicensis (Hack.) Dandy had high colonising ability. Survival of individual species was generally similar at both sites except for Urochloa mosambicensis. Heteropogon contortus and U. mosambicensis at ‘Hillgrove’ were short-lived (<10% survival after 4 years), B. ewartiana, Themeda triandra Forssk. and Aristida spp. had intermediate survival (10–50%), and C. ciliaris, C. fallax, B. pertusa and U. mosambicensis at ‘Cardigan’ were long-lived (>50% survival). Annual survival rates increased with plant age, were higher in good growing seasons than in poor seasons, were higher for large plants than small plants, and were lower at high defoliation levels than where defoliation was less severe. The differences between species in ability to colonise and survive, and the small influence of management compared to seasonal effects on survival, are discussed to explain species performance in pastures.

FUNGOUS ROOT ROTS OF THE STRAWBERRY

1934 ◽  
Vol 11 (1) ◽  
pp. 1-17 ◽  
Author(s):  
J. H. L. Truscott
Keyword(s):  
Seasonal Variations ◽  
Root Rot ◽  
Mycorrhizal Fungus ◽  
Artificial Inoculation ◽  
Microscopical Examination ◽  
Relative Importance ◽  
Root Rots ◽  
Growing Seasons ◽  
Obligate Parasites ◽  
Wild Strawberry

This paper reports the results of two years of investigation at the Horticultural Experiment Station at Vineland, Ontario, on fungi associated with the root rot of strawberries. Roots from the field were collected periodically throughout two growing seasons and were studied by direct microscopical examination and by plating methods. Hundreds of isolates from diseased roots were tested by artificial inoculation of strawberry roots, and the primary parasites were further studied. These were classed in the following genera: Pythium, Fusarium, Alternaria, Ramularia, Rhizoctonia, Verticillium and Cylindrocladium. Microscopical examination revealed three additional forms, Asterocystis, a Plasmodiophoraceous fungus and the Phycomycetous mycorrhizal fungus, which are obligate parasites of Phycomycetous type. Some of the fungi occurred more frequently than others, and there were seasonal variations in the activity of most of them. A similar root flora was encountered in wild strawberry roots, so that most of these fungi are probably indigenous. Their relative importance can be determined only by several years of observation of field material.

Soil nitrogen changes under continuously grazed legume-grass pastures in subtropical coastal Queensland

1972 ◽  
Vol 12 (58) ◽  
pp. 495 ◽  
Author(s):  
I Vallis
Keyword(s):  
Soil Nitrogen ◽  
Short Term ◽  
Heteropogon Contortus ◽  
Growing Seasons ◽  
Digitaria Decumbens ◽  
Total Soil ◽  
Stylosanthes Humilis ◽  
Average Rainfall ◽  
Chloris Gayana ◽  
Total Soil Nitrogen

Net changes in total soil nitrogen were measured in 1.2 to 2.4 hectare paddocks of legume-grass pastures at three sites. The sites and pastures were (a) Rodd's Bay-a pasture of Stylosanthes humilis and Heteropogon contortus, (b) Samford-a pasture of Phaseolus atropurpureus cv. Siratro, Digitaria didactyla, and Axonopus affinis and (c) Beerwah-a pasture of Desmodiam intorum cv. Greenleaf, D. uncinatum cv. Silverleaf, Lotononis bainesii, Trifolium repens, Digitaria decumbens, Chloris gayana, Paspalum dilatatum, and P. commersonii. At Rodd's Bay, the changes under pasture containing Stylosanthes humilis varied greatly according to seasonal conditions. During a period of 29 months that covered three successive growing seasons with below-average rainfall, short-term fluctuations in total soil nitrogen gave a net decrease of 70 kg ha-1 (0.95 confidence limits �30), an average of 29 (� 12) kg ha-1 year-1. In the following three-year period, which included two very wet growing seasons and one very dry one, soil nitrogen increased by an average of 30 � 10 kg ha-1 year-1. Over a period of four years, soil nitrogen increased by an average of 44 � 9 kg ha-1 year-1 under Phaseolus atropurpureus at Samford, and 81 � 10 kg ha-1 year -l under the mixture of legumes at Beerwah.

scholarly journals Primary Inoculum Sources of Monilinia spp. in Spanish Peach Orchards and Their Relative Importance in Brown Rot

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1048-1054 ◽  
Author(s):  
M. Villarino ◽  
P. Melgarejo ◽  
J. Usall ◽  
J. Segarra ◽  
A. De Cal
Keyword(s):  
Latent Infection ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Relative Importance ◽  
Inoculum Sources ◽  
Primary Inoculum ◽  
Ebro Valley ◽  
Growing Seasons ◽  
Fruit Orchards ◽  
Peach Orchard

Immediately following the identification of Monilinia fructicola in a Spanish peach orchard in the Ebro Valley in 2006, this orchard and two other orchards in the same valley were intensively sampled for potential tree and ground sources of primary Monilinia inoculum before and during three growing seasons between 2006 and 2008. Overwintered Monilinia spp. produced inoculum from only mycelium, and no apothecia were found in any of the three orchards over the three growing seasons. Mummies on trees were the main source of primary inoculum. More than 90% of Monilinia isolates on all fruit mummies were M. laxa. Positive relationships were found between (i) the number of mummified fruit and the incidence of postharvest brown rot (P = 0.05, r = 0.75, n = 8), and (ii) the number of mummified fruit and nonabscised aborted fruit in the trees and the number of conidia on the fruit surface (P = 0.04, r = 0.71; P = 0.01, r = 0.94, respectively, n = 8) and the incidence of latent infection (P = 0.03, r = 0.75; P = 0.001, r = 0.99; respectively, n = 8). In addition, the numbers of mummified fruit and pruned branches on the orchard floor were correlated with the number of airborne conidia in the orchard. Based on the results of these surveys, the control of brown rot in stone fruit orchards is discussed.

The relative importance of luminal and systemic signals in the control of intestinal iron absorption

2001 ◽  
Vol 120 (5) ◽  
pp. A678-A679
Author(s):  
G ANDERSON ◽  
S WILKINS ◽  
T MURPHY ◽  
G CLEGHORN ◽  
D FRAZER
Keyword(s):  
Iron Absorption ◽  
Relative Importance ◽  
Intestinal Iron Absorption ◽  
Systemic Signals
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