I am going home worried.” That simple message was uttered by a number of growers leaving Oak Park last week and it largely centred around the stations that dealt with grass weeds and herbicide resistance.

The pace at which grassweeds are appearing in new areas around the country is somewhat alarming.

There are many questions about how this spread is taking place but there are probably more questions that need to be asked as to why problems are not being noticed and addressed until they have become relatively serious.

Part of the reason for this is the lack of awareness or the risk involved and the ability of the weed to spread and multiply.

The real challenge must be to keep it out of your land and that is no small task in today’s farming systems. But given the many ways it can appear initially, the advice from Jimmy Staples, at the Teagasc crop trials event last week, was the best you can get or take – “get out there and walk your crops”.

Pulling and taking away even a few heads now could be a really good use of your time and save you years of targeted activity.

Driving through is not enough

Jimmy emphasised that it is not enough just to drive the tractor through the tramlines. The driver is unlikely to stop to pull a plant and strays may not even be noticed until they form a relatively dense patch. Neither is the driver likely to take a note to come back to find it. This is one of the major reasons as to why grassweed problems are continuing to expand around the country.

Finding that first plant is like the proverbial “needle in the haystack”, but you can’t find it if you don’t look.

Zero tolerance is the only good approach to keeping grassweeds out. This means identifying where infestation could come from, tackling and tracking the risks that must be taken and eliminating any potential risks that are not essential.

The main sources of weed infestations are seed, machines and organic manures. But seeds can also be carried on to your land by birds, soil, wildlife or even people. Some of these represent a greater or lesser risk. Some are controllable and some are not. Others are completely unpredictable.

Seed

Seed source is possibly the greatest single risk, as infested seed could bring a problem weed all across your farm in a single season. For this reason, Irish certified seed must be your priority. The Irish seed trade operates a zero-tolerance policy for most grass weeds, while certified seed from other countries allows a small tolerance.

We are now very conscious of the risk of contamination in wildflower mixes but we might also ask about catch crop seed or fodder crops that are imported.

We might also question imported oilseed rape seed in this regard. Some vigilant farmers point a finger at how they found blackgrass in the crop following rape.

While you would have to be very vigilant to find a single new plant, once you can see a patch the problem had been there at least one or two years. When a field infestation becomes obvious, this could have appeared initially five to eight years earlier.

Using seed from non-certified sources is a greater risk again. This should be regarded as a non-runner for anybody who has land that is still free of blackgrass.

Machinery

New problem weeds can be both introduced and spread by machinery. Any machine coming from land that is already infested with unwanted weeds can bring it on to your land. This could be a contractor or a shared machine.

We immediately think of combines and balers as being the greatest risk but seeds can also come on tractors or sprayers doing a late-season job like glyphosate.

While combines and balers present the most obvious risk in terms of bringing a weed on to your farm, they are also risky in terms of spreading a weed throughout your own farm if you do not know it is there.

Imported tillage machinery from Britain is a particular risk so make sure it is very well cleaned down before taking it out into your land. Do this on concrete rather than in a field. Even after doing that, record where it was first used and the direction it travelled in case a new problem arises later.

Other machines like straw-turning rakes or even cultivators can also carry in or act to spread and transfer seeds within a farm. So, once you let a problem in it becomes very difficult to contain if you do not rogue the first few plants. Make sure to clean down any machines coming on to your farm but do the same before you move from field to field if you know you have a problem in one.

Organic products

Organic products that may have originated from imported straw, or even imported grains that were processed by rolling rather than milling, should all be regarded as having a level of risk. This may not be justified but it is better to be safe than sorry so keep a detailed record of where products were used for future reference. It could give you a record of how a problem started and where else it is likely to be.

Clean machines

It has become increasingly important to ensure that machines that travel from farm to farm, or sometimes from field to field, are cleaned down thoroughly before entering land that is not infested. This might seem like a lot of work but failure to do it could be the cause of having a lot of extra work for 10 plus years to try and eliminate a problem.

People and wildlife

Blackgrass plants can shed approximately 70% of their seeds prior to harvest. So in situations where people are walking crops and moving from field to field, they can be a potential source of seed spread.

Seeds can get caught in clothes or boots and fall off elsewhere.

Birds can certainly bring unwanted seeds into land and especially around areas where they might perch, like electricity cables. Such areas should always be watched and inspected regularly. This risk increases considerably when there are more infested fields in the local area.

Other wildlife species might also spread seeds that get caught in their fur or they might pass seeds through their gut to increase seed spread.

Preventing grass weeds will stop serious problems

There are many ways that seeds can enter your farm. Because many of them are completely outside of your control, it is essential to walk every tramline in your crops. Do it twice between mid-June and mid-July when these weeds are most visible.

If you find plants of unknown grassweeds, get them identified and get rid of them.

If you have blackgrass, act before these plants flower and set seed. Low populations can be rogued and the plants removed.

Small patches of higher density incidents should be destroyed in situ, along with the crop, using glyphosate.

Bigger infestations could be removed as arable silage providing it is done before the blackgrass sets seed. Once viable seeds are produced, any further use of this material as silage or straw represents a risk of carrying seeds on to clean land.