This week I am going to take a relatively easy subject to discuss. Trials that I am currently doing, and why I think these areas need attention. I have carried out several field trials so far, but I’m starting to forge ideas for the areas that I really want to examine further, where there is real potential to improve what we are doing.

Field trials and experimentation remain the cornerstone of good agronomy; you can go with your instinct to a point, but ultimately good farming requires an objective and scientific basis. So here are some of the areas I am currently working on:

Maize Herbicides

Anyone will follows me on Twitter will be aware of my frustration with the lack of reliable grassweed herbicides in maize. Not only to control crop competition but to eliminate carryover of diseases on cereal volunteers.

Maize is highly sensitive to competition from weeds in the first few weeks of its life; weeds must be removed early enough, and prevented from re-appearing in the shamba for several weeks. The graph below is a classic experiment which shows this really well – yields suffer if you leave weeds for more than a week after crop emergence, and also suffer if you allow them to come back before the crop is 5-6 weeks old.

So any herbicide applied needs to have enough persistence to last 5-6 weeks which is a tall order. That’s why in many countries the average number of herbicides applied to a maize crop is two, so that later weeds are well controlled by a second spray.

One of the main reasons for poor control is of course soil moisture at time of application, so it may take several trials in various locations to do this and really understand which herbicides or combinations and timings of products work best in different years. We can’t prevent dry weather, but we can look at sequences of products that are less affected by lack of soil moisture. Maize is extremely sensitive to weed competition in the first 2-6 weeks of its life, and money spent protecting yield is money well spent.


Barley Fungicides

The announcement that Bayer’s herbicide Skyway Xpro has been approved is a real bonus to cereal growers here. Containing the new SDHI fungicide Bixafen and the triazoles prothioconazole and tebuconazole, this will be an exceptional product on Net Blotch in Barley especially.

Having another mode of action will help protect the Triazoles from fungicide resistance development and improve control in difficult seasons.

I would argue that the prothioconazole dose is actually a bit low for the situations that we will be using it in, but generally I have used this product extensively in Europe and found it very effective. The data from our independent trials in the UK showed it to be less useful in Canola.

I hope that this will soon be joined by Syngenta’s new Solatenol product (rumoured to also be formulated with prothioconazole, and a very good option on Barley), and BASF’s fluxapyroxad (arguably the strongest SDHI on Septoria in wheat).

The main thing is to have healthy competition in the marketplace and good choice of fungicides available for growers.

I have a range of barley fungicide trials planned, to look at the key growth stages for controlling diseases, to identify the most cost effective way to protect the crop whilst achieving greater yields. My instinct is at this stage is:

  1. GS30 remains the most important timing
  2. In some high altitude areas with a long grain-fill period, more protection is needed later on
  3. A T0 (mid tillering) has been beneficial this year in high-pressure situations



Lots of people have very valid opinions on how to make glyphosate work best. But ultimately local weed populations can behave very differently depending on speed of herbicide uptake, temperature variations and spray water quality.

I am a big fan of trying out different combinations side-by-side to eliminate the effects of weather conditions. When we get some proper weed flushes in our fallows I will be looking at:

  • Water volume
  • Pressure and droplet size
  • Nozzle choice
  • Nozzle angle
  • Water pH
  • Inclusion of ‘spikes’ such as 2,4-D, mecoprop, sulfonyl ureas
  • Use of adjuvants (not a great fan personally, but on specific weeds they are useful)


Ausquest Open Day 2017

Sometimes trials simply aren’t enough, and you need to run with an idea and see what happens to really make progress! This year’s open day at Stuart Barden’s Ausquest Farm at Athi River was a real exhibition in how not to carry on blindly copying what your neighbour is doing, but to critically think about every aspect of your farming business.

Stuart emphasised the importance of water and soil management, including how he only runs over 14% of his field area with his Controlled Traffic System to limit soil compaction, and how monitoring water use by crops has allowed him to optimise the timing of planting to make the most of the available rainfall.

This was a field day that really did not shy away from the good (Chickpea crops thriving in the dry), the bad (heavily diseased Mung beans) and the Sorghum Silage that was waiting for equipment to arrive so that it could be harvested and ensiled as dairy forage. Sorghum uses a fraction of the water of maize, and provides a ‘break crop’ in Stuart’s rotation that is heavily based on pulses.

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