May 2010 edition
Timing critical for controlling pests and weeds
Darren McCormick, Agronomist, Landmark Normack, Wodonga
Autumn rain has brought renewed enthusiasm in producing relatively cheap home grown fodder for the first time in recent memory. It has provided the opportunity to increase margin over feed costs at a time when we are often feeling the pinch.
A group of farmers from the Kiewa Valley, together with local agronomists, are meeting regularly through the growing season to discuss issues and opportunities related to improving the amount of home grown feed that can be grown each year. Simply, the group will bring issues to the table relating to the production of home grown feed and the agronomy, related to improving the return on pasture investments. Group members will demonstrate alternative crops that may help fill feed gaps in times when ryegrass has become unreliable to provide direct grazed feed, such as early autumn and through summer. Notes from each meeting will be taken and published in the Mountain Milk Line, immediately following each group meeting to help the wider north east dairy community make timely forage and pasture management decisions.
A meeting was held on May 6 and the following topics formed the basis of discussion.
Broadleaf Weed Control and Red legged earth-mite (RLEM)
Now the weather has cooled off, the onset of winter weeds is imminent along with red legged earth-mite. Timing is the key to getting control right and almost exclusively; you need to attack broadleaf weeds early, using lower rates. It is likely that you will be able to time your broadleaf weed sprays and first attack on earth-mite in the one application.
RLEM
At the time of writing, earth-mite were beginning to appear on the higher parts of farms and seem to be targeting young sown pastures trying to establish themselves (zero and three weeks emerged). These pastures are at the most vulnerable to pest attack and should be checked regularly. If possible insecticide treatments should start on these paddocks. Insecticide selection will usually be for specific to target RLEM, but if lucerne flea is also a problem then more suitable chemicals are available to give better results.
Erodium – Crows Foot
A tough weed to kill but early attack gives great results over the full growing season. It is a difficult plant to get chemical into due to the fern leaf, especially once it has become advanced. Avoid allowing it to become advanced as chemical options are expensive and difficult to get right.
Capeweed
Relatively easy to eradicate if controlled early. There are several different options available depending on the pasture composition and maturity. As with all chemical treatments consult a trusted local agronomist as they will have been on a number of farms and seen results of different treatments. They are also in the best positions to become familiar with new products which come on to the market.
Patterson’s curse and Thistles
For best results these weeds should be controlled in the Autumn. Once again use an agronomist as there are a number of treatments available ranging in cost and effectiveness.
Chickweed
This weed can become a problem from May onwards and often appears following herbicide applications early in the year. Given the large number of paddocks that have been sprayed out pre-sowing, it is likely that it will be a larger problem this year. Chemical selection for this weed is difficult as it will often persist through applications if applied late. Some work has been done with ‘new’ chemicals which looks promising. Call your agronomist for more information.
The key is timing; low rates on smaller weeds will do a great job at lower cost. It gives a greater kill rate and enables you pastures to dominate and remove the opportunity for a more weeds to germinate. For all chemical use it is advised that you work with an agronomist to ensure you apply the correct chemicals and the correct rates in the correct conditions to ensure you gain the most effective control possible.
Fertiliser:
Nitrogen
With good summer growing conditions and an earlier (than in recent years) break, many weeds have used large amounts of soil nutrient and nitrogen in particular. Many farmers have used this early break to control some summer and winter grasses such as barley. In doing this, large areas were sprayed out for a complete kill and sown later than ideal (late April). This will prove to be a worthwhile exercise over the whole year, however it may create a shortage of grazable feed in the coming weeks as the perennial grasses, cereals and brassica/rye crops are grazed and need longer rotations (35+ days) to optimize their performance.
Some simple math’s on nitrogen show the responses and returns are definitely in your favour. If you think you can consume the extra feed going into winter, then applications of nitrogen in May will do a better job than in June, due to colder conditions moving into winter.
Currently nitrogen, as urea, costs $1.30kg per kg nitrogen (Urea at $600/tonne). Responses are expected to be at least 10 kg/ha Dry Matter (DM) per kg of nitrogen applied.
From this, your investment of $1.30kg for nitrogen, will give you 10 kg DM of pasture/crop, costing you $0.13 per kg or $130 tonne DM, which compared to grain, at approximately $200/t, is relatively cheap feed and therefore is well worth the investment - provided you can consume all of the extra growth.
For more information about the discussions or for agronomic support when choosing chemicals and rates please call Darren McCormick on 0457 604 703.
Results of good weed control leave clean productive pastures.
