Temperature relations of Perapion antiquum (Col., Curculionidae), a weevil introduced to control the weed Emex australis in Australia

Australian populations of the widespread Emex australis and the more restricted E. spinosa were tested for subspecific variation. The plants were grown for two generations in a glasshouse from seed collected from field populations. The results from growing the first generation showed that two groupings of E. australis could be made on the basis of hierarchical grouping analysis, but the populations were much more similar in the second generation and such groupings could not be made. There were no marked differences between E. australis populations from Australia and South Africa, although one from Hawaii was less vigorous than the others. Amongst Australian populations of E. spinosa, one from Western Australia was less vigorous than the others. It was also found that Australian populations of E. spinosa were generally similar to those from Portugal and slightly more vigorous than those from Morocco.

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Isozyme Variation in Australian and South-African Populations of Emex australis Steinh

Australian Journal of Botany ◽

10.1071/bt9900161 ◽

1990 ◽

Vol 38 (2) ◽

pp. 161 ◽

Cited By ~ 3

Author(s):

FD Panetta

Keyword(s):

South African ◽

Isozyme Variation ◽

Native Range ◽

Low Level ◽

Emex Australis ◽

African Populations ◽

Native Populations ◽

Australian Colonial ◽

South African Populations

Isozyme variation was surveyed at 25 loci in 65 Australian (colonial) and 21 South African (native) populations of Emex australis. Only one polymorphism, restricted in distribution to the eastern States, was observed in Australia. Three additional polymorphisms were detected in South African populations, but most (16) South African populations were indistinguishable from the Australian ones. Thus, the relative uniformity of colonial populations of E. australis reflects the low level of isozyme variation in many populations within its native range.

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Estimating yield losses in wheat resulting from infestation by doublegee (Emex australis)

Australian Journal of Experimental Agriculture ◽

10.1071/ea9740656 ◽

1974 ◽

Vol 14 (70) ◽

pp. 656 ◽

Cited By ~ 5

Author(s):

DJ Gilbey

Keyword(s):

Crop Yield ◽

Field Trial ◽

Yield Loss ◽

Wheat Yield ◽

Yield Reduction ◽

Yield Losses ◽

Seedling Mortality ◽

Emex Australis ◽

Percentage Yield

The effect of doublegee (Emex australis) density on wheat yield was studied in a field trial. Percentage yield reduction (y) was related to doublegee plants m-2 at 1 week (x1) and 8 weeks (x2) after seeding thus: y = 10.3 + 0.24 x1 r = 0.78*** y = 5.6 + 0.44 x2 r = 0.86*** showing that estimates of doublegee density could be used for forecasting crop yield losses before it is too late to spray. No further yield loss occurred when x1 was greater than 120 plants metre-2. Doublegee seedling mortality that occurred during the seven weeks between plant counts was strongly related to the initial counts (x1) thus: r = 0.88***.

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The effect of herbicides on doublegee (Emex australis) and associated pasture species

Australian Journal of Experimental Agriculture ◽

10.1071/ea9640185 ◽

1964 ◽

Vol 4 (13) ◽

pp. 185 ◽

Cited By ~ 3

Author(s):

GA Pearce

Keyword(s):

Active Ingredient ◽

Emex Australis ◽

Triazine Derivatives

The results of trials to control doublegee (Emex australus Steinh.) undertaken with some of the more recently developed herbicides are presented. Herbicides tested were dicamba, monuron, five triazine derivatives, diquat, 2,4-D, and D.N.B.P. Of these dicamba was outstanding. At the rate of 2 oz active ingredient per acre a complete kill of plants up to four inches in diameter was obtained. For larger plants the rate had to be doubled. The effect of each herbicide on the pasture species present is reported. The dicamba treatments eliminated clovers present but did not affect the grasses. The spraying was delayed until an optimum germination had occurred.

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Selective chemical control of doublegee (Emex australis) in legume pasture

Australian Journal of Experimental Agriculture ◽

10.1071/ea9770080 ◽

1977 ◽

Vol 17 (84) ◽

pp. 80 ◽

Cited By ~ 2

Author(s):

DJ Gilbey

Keyword(s):

Chemical Control ◽

Growth Stage ◽

Leaf Growth ◽

Growing Season ◽

Field Trials ◽

Emex Australis ◽

Selective Control ◽

Selective Chemical ◽

One Year ◽

Clover Seed

Seven chemicals were evaluated for selective control of doublegee (Emex australis) in legume pasture in 14 field trials conducted at several sites in Western Australia over three years. The effect of removing doublegee on pasture growth was studied in four field trials over the same period. Three hundred and fifty to 700 g a.i. methabenzthiazuron ha-1 gave good selective control of this weed except at Chapman and Wongan Hills in 1974 where the beginning of the growing season was poorly defined. The selectivity of bromoxynil and WL 6361 1 in one year of trials was similar to methabenzthiazuron but that of asulam and metoxuron was too restricted for practical use when doublegees were sprayed at the 2-4 leaf growth stage, 2,4-DB showed selectivity on doublegees with 12 leaves, and no herbicides were satisfactory on doublegees with more than 12 leaves at the time of spraying. Pasture growth and clover seed production was not substantially increased by controlling doublegee.

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Competition between wheat and two Emex species

Australian Journal of Agricultural Research ◽

10.1071/ar9840453 ◽

1984 ◽

Vol 35 (4) ◽

pp. 453 ◽

Cited By ~ 2

Author(s):

JD Williams ◽

RH Groves ◽

PW Weiss ◽

AO Nichols

Keyword(s):

Growth Index ◽

Nitrogen Level ◽

Replacement Series ◽

Nitrogen Levels ◽

Emex Australis ◽

Species Mixture ◽

Low Levels

Wheat was grown with either of the cereal weeds Emex australis or E. spinosa in two replacement series at different nitrogen levels to determine the relative competitiveness of the two weeds with wheat. Other planting combinations, including a three-species mixture, allowed comparison between the two Emex species with and without wheat. The two Emex species were more competitive with wheat at high levels of nitrogen than at low levels. E. australis was more competitive with wheat than E. spinosa, regardless of the growth index considered, at all but the highest nitrogen level. The results suggest that, where the two species co-exist, E. australis will suppress E. spinosa. The relative weediness of the two Emex species with wheat is discussed. We conclude that whilst the presence of E. spinosa seeds may reduce grain acceptability, the presence of E. australis plants may reduce wheat yields more than that of E. spinosa.

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