Some ecological factors influencing the proportion of loose smut (Ustilago nuda (Jens.) Rostr.) in wheat crops

1965 ◽  
Vol 55 (2) ◽  
pp. 303-306
Author(s):  
D. A. DOLING
1963 ◽  
Vol 43 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Ahmet Demirlicakmak ◽  
M. L. Kaufmann

The association between the incidence of loose smut (Ustilago nuda) and kernel location in 6-rowed barley was studied. With artificial inoculation, kernels from the upper portion of the spike yielded the highest incidence of loose smut. Central and lateral kernels yielded similar numbers of smutted plants.With naturally infected seeds, lateral kernels produced more smutted plants than central ones. The percentage of infected seeds from the upper, middle, and lower portions of the spike varied from sample to sample.Within individual samples of nine 6-rowed varieties of barley small seeds generally produced more infected plants than large or medium-sized seeds. Since lateral kernels are normally smaller than central kernels, these results supported previous findings that the former are more subject to loose smut infection than the latter.


Koedoe ◽  
2002 ◽  
Vol 45 (2) ◽  
Author(s):  
D.A. Edge

The Brenton Blue butterfly, Orachrysops niobe (Trimen, 1862) (Lepidoptera:Lycaenidae), is endemic to the southern Cape and is currently listed as Endangered. This study looks at some of the key ecological factors influencing the breeding success of the species—host plant abundance and condition, nectar sources, climate/ microclimate, and vegetation management techniques. The adult butterfly population was monitored over an entire breeding season; host plants were identified and individually monitored; and egg counts were done. This enabled the effects of a number of different management techniques to be evaluated (burning, cutting, physical removal of invasive elements, and combinations thereof). A fivefold increase in the population of O. niobe was observed over the breeding season. This increase was positively correlated to a similar increase in host plant abundance in the areas where cutting and physical removal of invasive elements was practiced. Burning, by contrast, appeared to have a negative impact on host plant and butterfly abundance over the same period. Impacts of other factors such as climate, nectar sources and the natural strength of the second brood are discussed. A hypothesis, of megaherbivore activity as the principal historical disturbance mechanism promoting locally favourable conditions for O. niobe to establish and maintain colonies, is proposed. Recommendations for reserve management and future research are made.


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