By David Jones, Broad Acre Agronomist, Msc. Agriculture
If 2017 was to be remembered for the late and under-whelming long rains, this year has been a lesson in being careful what we wish for and adapting to a turbulent ‘new norm’.
Looking back, many farms experienced annual rainfall well above their long term average, and my experience was a wide spread of planting dates as farmers battled to get onto wet fields and struggled to spray and fertilise crops. Thankfully the extended period of rains ensured reasonable yields for most crops – where the torrential rain did not cause waterlogging and soil damage at least.
The rains brought – temporarily at least – a reprieve from the worst Fall Armyworm that we saw in 2017, but very difficult crop marketing conditions for most grain crops as farmers as the industry battled with large stocks of maize in particular.
Kenya’s 2018 maize production is estimated at 46m bags (90kg), well above the 5 year average of 40m bags, while the wheat harvest is predicted at 3m bags against the 5 year average of 3.5m bags.
Significant cash-flow challenges to all farming businesses arose in September with the introduction of VAT on agri-inputs and there was no one in the sector – farmers and suppliers alike – who did not notice the pinch.
As we look towards 2019, a few things can at least be certain; there will be more mouths to feed, prices will remain volatile, the weather unpredictable and there will be more challenges than ever to overcome.
I hope that I have at least enlightened you on some of these challenges this year in our #ThinkAgronomy newsletters. Here’s to a prosperous and fulfilling 2019!
Maize Fungicides Show over 10,000 Ksh/ha Improvement in Margins
Up to 7% increase in yield and significant quality improvements have been seen in our maize fungicide trial in Nakuru this season.
Carried out in a commercial crop of Pannar 691, even the untreated plot yield yielded 9.9 t/ha or 44 bags per acre as disease pressure was very low, with no Rust and only small amounts of Northern Corn Leaf Blight late in the season.
The three major lessons for maize growers are very similar to other parts of the world and are firstly, use a strobilurin containing fungicide. Secondly, apply as late as possible to prolong green leaf area and grain fill. Thirdly, grain quality is massively improved with the grain from the untreated plots standing out with higher discolouration and Fusarium contamination.
Several fungicide were compared at Tassling with strobilurins showing a consistent response, whereas straight triazoles such as tebuconazole did not.
Timing of fungicide application was also compared using azoystrobin as a standard treatment; at 10 leaf stage, Tassling and Grainfill and combinations of the two applications. Later timings were far more consistent and the highest yield response of 7% (690kg or 3 bags/acre) gave an extra return 10,600 ksh per hectare after the fungicide cost). This is before the increased value and marketability of the grain is taken into account.
Smart Wheat Variety Decisions for 2019
Choosing the right variety is vitally important in growing a profitable and reliable wheat crop. Here we review the current options and some of the new varieties coming along in 2019.
Still very high yield potential, if the Stem Rust can be managed. The wet long rains this year showed that Septoria also needs to be planned for in this variety – as a general rule the longer a variety takes from tillering to flag leaf emergence, the greater the risk of Septoria. Tillering needs to be promoted with early nitrogen but standing power (resistance against lodging) is good. Quality = average-good.
The last two seasons have highlighted Hawk as a fair weather variety; in a high rainfall season it can do very well and we have seen up to 10 t/ha spot yields with the variety on a field scale. The variety does not suit drier conditions however and struggled when planted later this year and in the dry of April in 2017. Stem Rust resistance has definitely broken down and similar fungicide input to Robin is needed to keep it clean. Quality = average but variable.
Quicker maturity than Hawk and Robin and a more aggressive growth habit, but around 5-10% lower yielding in the best conditions, albeit with highly marketable grain. Stem Rust resistance is slightly better than Hawk, and the performance in dry conditions is notably more stable than Hawk. Can be a slight sprouting risk so harvest this variety as a priority. Caution with Nitrogen as lodging can be a risk. Quality = excellent.
There is no pure high grade Kwale seed left so the variety will always look untidy, but since 1987 Kwale has proved consistent in both dry and wet conditions. Probably 5-10% off the best newer varieties when grown in perfect conditions, early Yellow Rust needs to be managed but Stem Rust tolerance is good (variety is not truly resistant; so grain quality can suffer even in the absence of visual disease as the plant expends energy to defend itself). Flowering is very protracted so timing of the ear spray for Fusarium can be tricky. Quality = average-good.
A very fast variety that is limited in its adaptability to hotter, drier areas. Yield potential when grown at altitudes upwards of 1900m is likely 20-30% lower than Robin, Hawk etc but in hotter areas the fast (110 days) maturity is extremely useful. Stem Rust resistance is moderate, and selecting the appropriate seed rate can be a challenge to balance tiller numbers with appropriate crop density and moisture use. Quality = good.
Suited to 1800-2000m, Wren’s Stem Rust resistance is moderate and maturity is similar to Korongo but with bold, red grain. Distinctive in appearance with droopy flag leaves and a dense canopy, with very good tolerance to acid soils. Yield potential still tends to be slightly below Korongo in most situations, and the variety does not perform well in the Highlands (Molo, Mau Narok, Timau). Quality = good.
A well-adapted variety to both medium and higher yielding environments, but Fusarium resistance is very poor and the variety is not particularly competitive against grass weeds early nitrogen can go some way to improving crop cover, but Tai suffers from slightly weak straw so caution is needed. Quality = good but variable.
Newer Varieties on the Rise
Eldo Baraka and Mavuno
Two very good varieties from the University of Eldoret. Excellent Stem Rust resistance but high lodging risk with weak straw. On the highest yielding sites this has limited the yield potential in our trials to 20% below Hawk and Robin. On two lower yield potential sites the yield was closer to the mainstream varieties. Grain quality at all three sites this year has been poor with Bushel weights in the low 70kg/hl. Good varieties but nitrogen and seed rates need careful management.
A slow developing variety around 2 weeks later in maturity than Kwale. Very good in dry conditions when early sown, and in a red soil will not bolt or shed tillers for 5-6 weeks without rain when most Kenyan varieties would last just 3-4 weeks before yield potential was severely reduced. In good conditions yield is at or above Hawk and Kwale, but Troy’s place is sown early to spread planting workloads.
Short, stiff straw and tillers well but Septoria needs managing and Stem Rust resistance is low to moderate so avoid in areas such as Njoro or Naivasha. Watch sprouting at harvest and cut as a priority.
Similar to Troy with slightly taller straw and weak on Septoria. Tillers well and holds onto tillers in dry conditions. Suits early planting but yield potential is at least 10% below Troy and Kwale.
An early maturing CIMMYT variety with bold white grain that has yielded as well as Hawk and Kwale but is 2-3 weeks earlier. Superb Stem Rust resistance and stiff straw make this a very promising variety, but for now treat the risk of sprouting with caution until we have more data.
Another variety from CIMMYT that has shown promise with very good head size and Stem Rust resistance. Benefits from early nitrogen to help it tiller, and Yellow Rust needs watching in areas such as Mau Narok and Naivasha. Early trials put the yield on par with Korongo with slightly earlier maturity.
Most Common Maize Nutrient Deficiencies Revealed
Nutrient deficiencies are often ‘silent’, going unnoticed unless their visual symptoms are particularly pronounced. Reviewing the Leaf Nutrient Analyses results from samples received from across Kenya in 2018, the most commonly seen are:
- Magnesium – costly to yield, very widespread and easily rectified with Magnesium Sulphate foliar sprays although several applications may be required. It is worth placing Magnesium Sulphate in-furrow at planting to check the effectiveness, as many soils lock up Magnesium and results can be disappointing but it can also work very well.
- Calcium – response to Calcium (from Lime, Gypsum or foliar calcium applications) is not well documented in maize, but a liming program to correct acidity will rectify this and provide improvements in other areas too. We have work ongoing looking at calcium response, but in-furrow granular lime has been disappointing in the past.
- Boron – virtually impossible to detect early on, but very visible as poor kernel set on the cob at maturity, particularly when the tip of the cob has not set seeds (Boron vital for pollen germination and pollen tube growth). Responses are very common but remember that Boron goes quickly from deficient to toxic, so do not overdose and if using in-furrow, keep it away from the seed.
Fall Armyworm; what does 2019 hold in store?
Most technically-minded farmers and agronomists have a clear idea of their Fall Armyworm programs for 2019 already, including how to get the crop out of the ground and competitive as quickly as possible (good nutrition and accurate planting), how they plan to scout and monitor populations, and what spray program to employ to protect the crop.
This year I showed the results from two studies where I investigated the efficacy of a range of insecticides against Fall Armyworm. Conducted in the laboratory to try and control many of the variables I have encountered when attempting field trials, these have at least highlighted the effective – and less effective – chemicals at different stages of the larvae’s life cycle.
More trials have been conducted since and I am beginning to question whether there is a partial resistance developing to some chemicals, given the patterns that I have observed over the past two years.
The development of resistance to various active ingredients is an inevitability so control of Fall Armyworm will not get any easier. That is why good stewardship and rotation of active ingredients by the industry is vital.
We got away lightly this year generally speaking as the rains supressed Fall Armyworm populations, but we must not drop our guard in 2019. Rotate different modes of action, spray preventatively and focus on accurate and safe application with competitive crops to minimise damage.
Farming for the future requires a change of approach. Monoculture, soil degradation and climate change and soil degradation are threats to the future of 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,
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.