The imi herbicide Imazethapyr will shortly be released in Kenya, giving us another tool for weed control in a range of crops. This is great news, and there are several places where it will fill important gaps in our herbicide programs.

Herbicide Imazethapyr

The Group B or SU herbicide has useful activity on Fat hen, Wild Radish, Nightshade, Amaranthus and Setaria Grasses. I can see it slotting into herbicide programs for legumes, in particular for example, to improve control of canola (non-Clearfield) volunteers, Nettle Leaf Goosefoot with other pre-emergence mixtures.

The really interesting part for me will be what it can do on our species of Brome (if anything!). I have had successive false dawns and disappointment where products that work well on Bromus diandrus, rigidus and Anisantha sterilis have achieved zero control in our species of Brome. I will update on our trials in a future edition of #ThinkAgronomy.

Plant-backs and following crop restrictions should be carefully observed, and remember to seek advice and follow the label if in doubt – it is there for you and your crop’s safety.


Crop Safe planting interval
Barley 10 months
Oats 22 months
Wheat 10 months
Canola (non-CL) 34 months
Peas / beans / Chickpeas 0 months
Maize 10 months
Sunflowers 22 months

Boosting livestock performance with high quality whole crop silage

Producing and storing high quality forage is not always easy, but on one arable and livestock farm we have used a mix of peas and barley to produce a high energy, protein dense forage that can be easily mechanised.

The important factors are that the ingredients in terms of seeds are available here already, and it is simple.

The barley and peas mix was planted with a notill seeder at 40kg/ha Barley and 80kg/ha peas, and treated with pendimethalin pre emergence. The beauty of using peas as opposed to many other legumes is the option to use bentazone post emergence, the ready availability of seed, and the fact that one rarely out competes the other, giving a predictable mix.

Cut at the soft dough stage when the grain can rubbed into a ‘cheese’ consistency between the fingers, the silage produced measured 45% dry matter and contained 10.2 MJ of metabolisable energy and nearly 12% protein. Yields of 20-25 t/ha fresh weight are easily achievable.

silage making

We used a flail chop forager, which limits the ability to chop the material finely down to 4-5cm, making it more difficult to ensile and easier for the animals to ‘sort’ when mixed with concentrates in the trough.

Firming the clamp by rolling with a heavy tractor is crucial to expel air and promote anaerobic fermentation, and sheeting the sides and top of the clamp to seal it is crucial – even overnight between fills. Bacteria such as lactobacillus that are naturally present on the material will convert sugars to lactic acid under anaerobic conditions.

An alternative option is mixing Urea which is converted to ammonia in the clamp, preserving the silage and increasing Crude Protein content. The palatability and intake potential can decline however, and the urea needs to be carefully mixed to avoid potential danger to livestock at feed out.

We added molasses, which in retrospect was not a good idea. Having discussed with a ruminant nutritionist, he felt that adding sugar in the absence of effective lactobacillus population or inoculant can cause the clamp to heat as undesirable bacteria consume the sugar, thus consuming and wasting some of the energy in the feed.

This is a particularly good mix for a bad Ryegrass field that needs cleaning up in the arable rotation – Ryegrass would add immensely to the sugar content and ensiling potential.

Going forward, the silage could be improved further by choosing an earlier maturing variety of barley (e.g. RGT Planet when released) and a later variety of peas (Bagoo is currently in National Performance Trials), to get closer to the optimum cutting stage for both the peas and barley.

We would definitely advocate using a good quality inoculant next time, and a finer chop length to improve consolidation of the clamp.

Center of Excellence for Crop Rotation Agventures

Farming for the future requires a change of approach. Monoculture, soil degradation and climate change and soil degradation are threats to the futureof how we feed the planet. Agventure Ltd set up the Center of Excellence for Crop Rotation to help farmers diversify cropping systems and introduce techniques which have a long-term outlook to improve soil health. The Center of Excellence for Crop Rotation works extensively with Crop Nutrition Laboratory Services Ltd (CropNuts).

Till next time,

Happy farming,


David Jones

About David

David Jones is the Broad Acre Specialist at Crop Nutrition Laboratory Services Ltd. (CROPNUTS). David has a keen interest in soils and no till farming systems where he has undertaken work looking into weed levels and changes in soil structure, and has extensive experience in field trials and in the development of precision farming techniques. In his spare time he enjoys playing rugby.