Showing papers on "Heterodera avenae published in 1978"
TL;DR: The occurrence of both cereal cyst nematode (H. avenae) and Rhizoctonia solani in patches of poor wheat in a field trial in South Australia indicate a possible association between these two pathogens.
Abstract: Field trials in a sandy mallee soil in Victoria have shown that large increases (up to 323%) in grain yield are obtained by soil fumigation or the application of nematicides. Development of the plants was enhanced by control of soil-borne root pathogens. The occurrence of both cereal cyst nematode (H. avenae) and Rhizoctonia solani in patches of poor wheat in a field trial in South Australia indicate a possible association between these two pathogens. Glasshouse studies showed that the effects of H. avenae and R. solani on wheat were greater when both pathogens were together than with each individually.
35 citations
20 citations
TL;DR: Variations in the number of females that developed on resistant cultivars were partly due to the relationship between induced resistance and inoculum density, and it is unlikely that the few females that development on the resistant cultivar represented a more virulent race of H. avenae.
Abstract: The number of larvae of H avenae penetrating, establishing and developing at different inoculum densities in susceptible (cv Halberd) and resistant (cvs AUS 10894 and AUS 90248) wheat was similar when only one root per seedling was inoculated At low inoculum densities, similar numbers of adult females developed on the three cultivars, but when the initial density was increased, fewer females developed on resistant roots and fewer developed on AUS 10894 than AUS 90248 (Loros) When the same root of AUS 10894 was inoculated twice, larvae in the second inoculation did not penetrate Resistance was induced within 12 hrs Such induced resistance was not transferred to uninoculated roots of the same seedling Variations in the number of females that developed on resistant cultivars were partly due to the relationship between induced resistance and inoculum density Therefore, it is unlikely that the few females that developed on the resistant cultivars represented a more virulent race of H avenae
9 citations
TL;DR: The number of larvae of Heterodera avenae which penetrated a root of wheat increased linearly as density of inoculum increased until a maximum was reached and the duration of the lag phase decreased as inoculum density increased.
Abstract: The number of larvae of Heterodera avenae which penetrated a root of wheat (cv. Halberd) increased linearly as density of inoculum increased until a maximum was reached. Which root of the seedling was inoculated did not affect the number penetrating but placing sand on the root tip before inoculation increased the number of larvae which penetrated. When the roots were exposed to larvae for longer periods there was generally a similar change in the numbers penetrating a root, except that there was an initial lag phase and that a constant number was not maintained at high densities. The duration of the lag phase decreased as inoculum density increased. With increased duration of exposure of the root the number of larvae established or immobile within the root increased linearly till constant. Longer storage of larvae prior to inoculation increased the number of immobile larvae within the root. The number of larvae penetrating single roots of wheat and barley (cv. Clipper) was the same, but barley developed more seminal roots during early seedling growth than wheat. Tolerance in barley to H. avenae was attributed to the dilution of the number of larvae in each root tip because of the increased number of roots.
5 citations
TL;DR: It may be assumed that intensive growing of nematode-resistant cereals includes a risk of promoting the occurrence of pathotypes other than the 2 known to exist in Denmark, and so far, there is no indication for their existence.
Abstract: On the basis of investigations on the cereal cyst nematode's distribution, it is presumed that one third of all the cereal growing areas in Denmark is infested to a degree, and that yield losses of 5 % or more may be assumed. This means an annual loss of about 100 million D.Kr. By using resistant cultivars every second year, the population of Heterodera avenae Woll. can be kept at a harmless level. It may be assumed that intensive growing of nematode-resistant cereals includes a risk of promoting the occurrence of pathotypes other than the 2 known to exist in Denmark. So far, there is no indication for their existence.
4 citations
TL;DR: The life-cycle of the cereal cyst-nematode was studied on oats, wheat and barley and the number of juveniles that must invade for one female to be produced was used to assess host efficiency.
Abstract: The life-cycle of the cereal cyst-nematode was studied on oats, wheat and barley. There were differences in the rate of hatching, invasion by juveniles, rate of development, sex-ratio and rate of multiplication. The number of juveniles that must invade for one female to be produced was used to assess host efficiency. The ultimate efficiency of the host was not always expressed during the early stages of the nematodes' development.
4 citations