The control of doublegee

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Journal of the Department of Agriculture, Journal of the Department of Agriculture, Western Australia, Series 4 Western Australia, Series 4

Volume 8

Number 4 1967 Article 4

1-1-1967

The control of doublegee The control of doublegee

Geoffrey A. Pearce

Follow this and additional works at: https://researchlibrary.agric.wa.gov.au/journal_agriculture4

Part of the Agronomy and Crop Sciences Commons, Plant Biology Commons, and the Weed Science Commons

Recommended Citation Recommended Citation

Pearce, Geoffrey A. (1967) "The control of doublegee," Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 8: No. 4, Article 4.

Available at: https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol8/iss4/4

This article is brought to you for free and open access by the Agriculture at Digital Library. It has been accepted for inclusion in Journal of the Department of Agriculture, Western Australia, Series 4 by an authorized administrator of Digital Library. For more information, please contact [email protected].

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Doublegee was introduced from South Africa as a vegetable by early settlers. It competes strongly with crop and pasture

and its spiny fruits cause lameness to stock

G. A . PEARCE M.Sc. ( A g r i o ) , Biological Services D i v i s i o n

FOUR years ago no practical recommendations could be made f o r the control o f doublegee. W i t h money provided by the State W h e a t Research Fund, research has been under- t a k e n i n t o the c o n t r o l of this weed, and there is now no reason w h y most farmers cannot b r i n g doublegee under control.

Herbicides are available for selective control in crops, while good pasture management will nullify doublegee's effect as a competitor.

Significance

Doublegee has proved to be one of the most troublesome weeds in Western Aus- tralia. It competes strongly with crop and pasture during the important early growth stages. A heavy stand can reduce cereal yields by as much as 10 bushels per acre, while the smothering growth of vigorous doublegee plants can significantly retard pasture species.

Doublegee is most active during the early winter and usually by August and Septem- ber it has finished its growth cycle. The hard seed cases remain for many years after the seeds have germinated, and large numbers build up within a few years. As many as five and six million per acre can be present and the rigid spines of these seed cases cause severe lameness in stocK, particularly when they are travelling.

Control

There are few districts in the State where doublegee does not occur, although it is most important in the wheat growing 150

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I N BRIEF . . .

• Doublegee growing in a cereal crop can be controlled by spraying w i t h linuron (Afalon or Linuron 50) when the cereal is in the two leaf

stage. W h e n the crop has begun to tiller, dicamba (Banex or Banair) should be used.

' • Herbicides are not recommended for the control of doublegee in pasture.

• The production of a good legume- based pasture, w i t h heavy grazing u n t i l the clover or medic begins to flower, w i l l overcome the doublegee problem.

• The pasture management suggested is the same as that recommended as normal good farm practice.

Perhaps the grazing should be slightly heavier than usual.

• The year after such management the doublegee is not a problem and the pasture is usually ahead of one which has little or no grazing.

districts. It is found in most coastal towns, and in fact any place where farmers are inclined to visit. This is because the spiny fruit find rubber tyres ideal for distribu- tion. Other important "carriers" of doublegee are stock, hay and poorly graded lines of clover seed.

Although an annual, doublegee is a particularly difficulty weed to control because of several characteristics:

• The plants seed freely and the first seeds are formed at an early stage of growth.

• The fruits are well adapted for spread- ing, and

• The protected seeds can remain viable for many years.

Seed dormancy

Long term control of doublegee is great- ly affected by the conditions which govern dormancy of the seed. It has been observed for many years t h a t a heavy stand of doublegee follows cultivation, particularly in the year after a cereal crop has been grown.

Once an area has gone back to pasture, the stand of doublegee is likely to decline over a period of several years, if the pasture contains a good pasture legume.

The doublegee problem usually remains unimportant until the area is again cultivated and the cycle starts again.

Trials during the past four years have established certain patterns of behaviour of doublegee and it no longer appears to be as difficult to handle as in the past.

Very little seed emerges from a depth greater than two inches, and if seed is left undisturbed, practically no germination occurs from any depth after two years.

Compaction of the soil prevents air coming into contact with the seed and induces the seed to remain dormant. The normal stand

°f doublegee in pasture invariably comes from seed formed in the previous two years.

The time during which doublegee seed can remain in the soil and germinate at a iater time, depends upon a number of conditions. However, in general, it is found that a large proportion of buried seed degenerates or is eaten by insects within a

few years. This is fortunate when the large Quantity of seed formed is considered.

Despite this loss of seed there appears to

be enough viable seed left in most situa- tions to ensure a new infestation when the ground is again cultivated.

Control in cereals

Two herbicides can be recommended for the control of doublegee growing in a cereal crop. Both are highly effective if applied correctly, and there is little risk to the crop. A complete kill can be expected where the doublegees are growing under favour- able conditions, but where the plants are under stress results may not be so good.

An increased rate of application is often required to achieve worthwhile results.

LINURON:

Linuron is a wettable powder, sold under the two trade names of Afalon and Linu- ron 50. It not only kills doublegee but is also effective against a wide range of other broad-leaved weeds.

151

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A heavy stand of doublegee such as the one pictured in this oat crop can reduce crop yield by as much as 10 bushels an acre. A single spray treatment overcomes the problem

The recommended rate of application is 8 ounces of the commercial product per acre, applied before the doublegees are more t h a n two inches across. This is usually when the cereal is in the two-leaf stage

and approximately three weeks after plant- ing. Once the doublegee are two to four inches across, it is necessary to increase the rate to 12 ounces per acre. When the plants are larger t h a n this it would be necessary to consider the use of Banex.

The main advantage in using linuron is that the doublegees can be killed while in the seedling stage, and this growth stage is when they have their greatest effect as competitors with the cereal.

Because linuron is a wettable powder it is necessary to keep the spray solution agitated to prevent the linuron from settling in the spray tank.

DICAMBA:

Dicamba is the active ingredient in the commercial products Banex and Banair.

It is particularly effective against doublegee but because of the susceptibility of cereals it is necessary to delay spraying until the crop is in the early tillering stage, some six to eight weeks after plant- ing.

Banex is not effective against other common crop weeds such as radish and turnip, and when these are present 2, 4-D amine should be added to the mixture.

For aerial application Banair is available.

This is an oil-based formulation which can be used with 2,4-D ester, so giving control of a wider range of weeds.

Where doublegee is growing in a pasture the effectiveness of herbicides is variable. In this trial at Chapman Researc"

Station the pasture was killed as well as the weed. The answer lies in good pasture management and heavy grazing

152

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Doublegee is a f a s t - g r o w i n g annual, a n d i t s broad leaves quickly s m o t h e r small p a s t u r e piants. Heavy g r a z i n g keeps the weed i n c h e c k a n d allows the pasture l e g u m e t o g r o w a n d

set seed

The rate of application required for the control of doublegee is one half pint of Banex or Banair per acre. This rate will kill doublegee plants as large as six inches in diameter. For bigger plants the rate should be increased to f pints per acre.

Control in pasture

There is no herbicide to control doublegee growing in a pasture, which is not likely to do some damage to pasture legumes. Even where the clover is not killed growth is often retarded, while the severity of the treatment varies considerably ac- cording to the conditions prevailing at the time of application. Linuron has given good

selective control on several occasions, yet at other sites has practically killed all broad leaved plants. Banex is particularly severe on legumes. For these reasons there is little to be gained by considering the use of herbicides, particularly when good pasture management will achieve control.

Competition from doublegee is greatest during the early growth stages of the pasture. With its broad leaves and flat growing habit, doublegee grows rapidly immediately after germination, while legume species are inclined to be stationary. Unless the growth of the weed is checked at this stage, within six to eight weeks a heavy stand of doublegee can com- pletely overshadow the pasture.

RECOMMENDED HERBICIDAL TREATMENTS FOR THE CONTROL OF DOUBLEGEE IN CEREALS T h e r a t e o f a p p l i c a t i o n is g i v e n i n t e r m s o f c o m m e r c i a l p r o d u c t s p e r a c r e

Growth Stage

'-2 inches

*-4 inches 4-6 inches

*-8 inches

of Doublegee Growth Stage of Crop

2 leaves 2-6 leaves

Early tillering ( 2 - 4 tillers) Tillering ( 4 - 6 tillers)

Herbicide

Linuron Linuron Dicamba Dicamba

Rate of Application

8 oz.

12 oz.

i pint i P>nt

Trade Name

Afalon or Linuron 50 Afalon or Linuron 50 Banex or Banair Banex or Banair

155

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For these reasons everything possible should be done to induce a dense, actively growing pasture and at the same time restrict the growth of the doublegee.

Where it is necessary to replant after cropping a high rate of seeding should be used, as recommended by the Department of Agriculture for pasture establishment.

Along with an adequate dressing of fer- tiliser this will ensure the rapid develop- ment of a complete ground cover and pro- vide the necessary competition for the growing doublegee.

This alone is not sufficient to control the weed, and it is essential to stock the area heavily enough to ensure t h a t the sheep keep the pasture short. In this way the doublegee will be eaten back, space will be available for the clovers or medics to grow, and when they begin to flower and set seed the doublegee will not affect their production.

Stocking should commence within a few weeks of germination and be maintained until the pasture plants begin to flower.

Heavy top growth on pasture reduces the amount of seed set, and the type of management suggested will result in maximum seed production.

Although doublegee contains oxalic acid and has caused odd stock losses, invariably this has occurred where the sheep have been forced to graze an area covered solely by doublegee. Where other plants are present there is little danger.

The compaction of the soil resulting from heavy grazing is also important because this discourages the germination cf dormant doublegee seed the following year. The heavy grazing will restrict seed formation by the weed so that the problem is practically non-existent in the second year.

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