March 15, 2024

AGRONOMY NEWS

Maize varieties for 2024

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Visiting the agro vets presents a bewildering choice at this time of year, as that all-important decision around which maize seed to plant comes closer. We take a look at some of the options available for 2024 for high and mid-altitude areas.

One of our maize trials in Nakuru in 2023.

Highlands

The choices for locations above 2,000m with good rainfall are vast. From Kenya Seed, H6218 does tend to be slightly higher yielding than 6213 in our trials but there is not much between the two; 6218 has better standing power and both varieties are very good against NCLB, Gray Leaf Spot and Rust. Something I always notice when I plant trials myself is that whilst the physical seed quality of these hybrids is often good, the crop is very uneven right from emergence. This does make for challenges with weed control and limits populations to 40-50,000/ha.

H6506 is an interesting, relatively recent variety that carries MLND resistance but it has not performed well in our trials, with the exception of off-season sites where we can verify that the MLND resistance is very good (plant height is very variable, so do not plant this variety with the expectation of harvesting it with a combine.

From Seedco, Tembo 73 is a very tall but more uniform variety compared to similar varieties in this category. Grain quality is relatively good but in Usain Gishu it can struggle with Gray Leaf Spot pressure, which is probably why the variety tends to perform slightly better in the South Rift where disease pressure is generally lower.

Pannar 691 is has been around for years and continues to be widely available. Grain quality is sometimes variable with Bacterial Rots around the cob sheath, but the variety still usually comes in the top third of highland maize trials that we run, and apart from a low level of NCLB the disease resistance has largely held up over the years. P3812W is arguably a better choice now, with better uniformity, higher yields and very good grain quality.

Last year we saw a lot of Stalk Rot in P3812W for the first time, but generally as long as you watch the Rust (two applications of azoxystrobin or pyracostrobin do pay in this variety), the grain quality is excellent. In trials it has been more responsive to higher populations than I would have expected.

It will be interesting to watch how new variety 9M-91 performs, but the MLND resistance is very welcome and standability is much improved over the likes of 6218, 691 and Tembo 73. We have seen some good yields in trials so far but it is too soon to be truly confident in any new variety, other than to say it is very leafy and produces a lot of biomass.

From Pioneer, it is surprising how often 30G19 hit the top of the table in trials. Not a pretty variety to look at, it has performed in the top few in trials at Moiben, Rumuruti and topped an entire trial in Timau of all places! It remains a solid and very adaptable hybrid.

 Drier areas such as Laikipia can often grow better maize than the traditional areas if the right variety is put into a well-structured soil, into stored moisture, with a crop rotation to give the roots a chance

 

Finally, do not discount DK 777 in highland areas. It is very erratic above 2,300m as it probably has too much tropical or sub-tropical material in its background; it does not like cold nights and anthocyanin production from stress is often confused with phosphorus deficiency. It rarely reaches the top 10% of yields in trials but grain quality and uniformity are excellent, and as such you can push the variety to higher yields in ways that you simply cannot with other hybrids.

Mid-altitudes

For altitudes below 1,800m there is more of a divergence in the type of maize variety required than is often realised. For areas such as Bungoma and Kakamega with high rainfall and humidity, disease resistance is the priority. DK 777 and DK 90-89 do very well in these areas, produce good grain quality, and 777 brings MLND resistance.

Seedco 61 has produced good yields in the past, but it hits a yield limit in good seasons that I have never managed to push through. NCLB is the disease to watch in 777 in these areas, which means you will need to apply more than just azoxystrobin. Pan 15 has good disease attributes but does need help with fungicides.

Kenya Seed 516 has very stable yields but is perhaps not the highest yielder (I have had H522 in trials on occasions and it is has possibly slightly higher yield potential, but both have a habit of producing smaller kernals), as is the case with Western Seed’s 505 and 507 varieties. In a drier season these relatively fast varieties do come into their own however, and is why I often like to test them in areas like Rumuruti where we can learn about their ability to cope with stress around tassling.

In mid altitude areas with tighter or less consistent rainfall patterns – for example Laikipia, it is all about getting the crop planted before the rain, into stored moisture and using the heat to drive the crop onto flowering before the rains finish. Disease resistance is far less of an issue in these situations, not least because maize would (hopefully) be in a rotation and not grown continuously. DK 777 is less suited to these areas as it is less drought tolerant (despite what I am regularly told, the trials data does not lie and is very clear that in drier seasons 777 underperforms).

7m-81 is a great variety for areas below 1,900m and has demonstrated very stable yields time and time again – it is arguably better suited to drier, mid-altitude areas than most mid-altitude material. Grain quality is not the best but it is good enough, and it has plenty of room to experiment with populations as it has quite a flexible ear.

Some of the most impressive and surprising results that I have seen with maize in recent years are in the more ‘marginal’ drier areas. Perhaps I am confusing these areas with good management; the conditions are less forgiving so they force farmers to go back to good husbandry; planting early into moisture, and with a crop rotation and well managed soil, to allow the crop to develop a deep root system.

DISCLAIMER:

  1. The information and recommendations for seed varieties, including quality, viability, and performance, are based on independent trials conducted by an independent agronomist. These results apply only to the tested seed sample and conditions. No warranty, express or implied, is provided for recommended seed varieties. The recommendation list is not exhaustive, and omission does not imply inferiority.
  2. Information and recommendations for seed varieties are derived from independent trials and the practical experience of an independent agronomist. Trials may not cover all conditions, and we do not guarantee similar results. Recommended varieties may not be suitable for all use conditions; the user must determine suitability based on local conditions and agronomic practices.
  3. This article’s information is for general consumer assistance, and we are not liable to any user for the provided information under any circumstances.

Optimising pea seed rates and row spacing

The best crops – maize, peas, wheat or canola – are almost always the ones that are planted immediately after peas. Legumes are all high risk crops however, and they don’t come much more high risk than peas, so we have focused some of our most recent trials work on keeping the upfront costs down as well as how to optimise yields.

The interaction between row width, seed rate and variety is an interesting one, particularly because wide rows have lots of benefits in peas; the ability to plant deep into moisture being a large seeded crop, to leaving standing stubble lines in place to support and shelter the crop, and occasionally to incorporate herbicides at planting.

We have run a series of trials with the two recently released varieties Karioka and Greenwich planted at 70 seeds per m2, and 100 seeds/m2. With each variety and seed rate at narrow 18cm rows and wide, 37cm rows. Whilst it is early days, the message so far is that the highest yields are achieved with narrow rows, and that this is more important than seed rate (assuming good establishment)

Site A: Laikipia January 2024 – planted on narrow rows into standing barley stubble.

Interestingly Site A in Laikipia was planted with the stubble still standing in the plots – which should have favoured the wider rows to keep the crop standing at harvest. There was very clearly an improvement from the narrower rows in both Greenwich and Karioka.

At site B in Timau, we only looked at 70 seeds/m2, but again the two highest yields were achieved at narrow rows for both varieties, and a 50:50 blend of the two varieties.

Site B: Timau February 2024 – planted on narrow rows into standing, fresh canola stubble (N = narrow 18cm, W = wide rows 37cm rows).

I have a feeling, which seems to be confirmed by these results, that varieties with narrow tendrils and a small growth habit such as Karioka tend to respond more to narrower rows than varieties with wide tendrils such as Greenwich, which can reach across the rows and support themselves at an earlier stage of the crop.

The key message so far is that unless there is a clear need to plant deep to reach moisture and get the crop established early, narrow rows produce higher yields, and that this is more important than seed rate. It can in practice also avoid the need for potentially damaging in-crop herbicides, by improve crop competition against weeds.

70 seeds/m2 certainly seems to be adequate in other trials that I am doing, but I need more results to make us really confident.

Set the seed rate according to the conditions on the day if the seedbed is poor and there are concerns over establishment; it is often best to wait with peas and to see if it is possible to fix it. After all, you will need a level and firm seedbed at harvest.

Pre-emergence herbicides for maize – reminders

Pendimethalin (e.g. Stomp) – not strong on Amaranthus, and with heavy rain can be washed down into the seed layer in lighter soils causing slight stunting and root pruning. Good for controlling grasses including Setaria but not great against Eragrostis.

Atrazine + S-metolachlor (e.g. Primagran Gold) – does a good job at covering most weeds including Amaranthus, Chinese Lantern, Conyza, Gallant Solider and Mexican Marigold. Full rate is often not required for the purpose of a pre em. Cleavers tend not to be well controlled, but chenopodium weeds such as Lamb’s Quarter are controlled for six weeks and has good activity on most grasses including Signal Grass, Eleusine, Brome, Setaria’s and Eragrostis and

S-metolachlor (e.g. Dual Gold) – Amaranthus, Gallant Soldier and useful suppression of Watergrass / Nut Sedge, as well as grasses including Setaria and Eragrostis, but poor on its own against Blackjack. Needs a partner in most situations.

Atrazine + acetochlor (e.g. Sigma Combi) – Similar spectrum of weeds controlled to atrazine plus metolachlor above, but weaker on most offers little control of Brome in higher altitude areas. Good on Eleusine and Portulaca.

Adengo (thiencarbazone + isoxaflutole) – I always found this to be very strong on Commelina, volunteer brassica weeds and Blackjack, but slightly weaker on Amaranthus. Generally needs to be mixed with something like linuron or metribuzin to stop these weeds becoming established. Wash the sprayer carefully after using Adengo.

Integrity (dimethenamid-P + saflufenacil) – Good of Gallant Soldier, Mexican Marigold and brassica weeds especially, but poorer on Amaranthus and Blackjack. Rarely sensible to use without a partner product to cover these quite significant gaps. Does have useful burndown activity but if Conyza or Mallow seedling are present you will still need to apply glyphosate – and apply it separately as the two are antagonistic (expect when <15g/ha of saflufenacil is used as a spike!)

Mesotrione + S-metolachlor + terbuthylazine (e.g. Lumax) – Covers every weed and gives several weeks of persistent. If you were looking hard for criticism it would be that at the full label rate the mesotrione is persistent for up to 9 months against many legumes and canola which may be planted straight after harvest in the off-season.

Surestart (acetochlor + flumetsulam + clopyralid) – Perhaps not quite as strong as mesotrione, metolachlor and terbuthylazine on Amaranthus, but good on Thistles, Chinese lantern and Cleavers. High rate of clopyralid means this product is very persistent in the soil against most legumes, so beware off-season beans. Wash out the sprayer VERY CAREFULLY when you have had flumetsulam in it.

Metribuzin – adds good control of Amaranthus and especially Blackjack, weaker on Nightshade and Cleavers.

Linuron – old chemistry that is often forgotten in maize but provides very useful control of Nightshade, brassica weeds and Amaranthus

Products may vary according to registration and availability in different countries. Always follow the label and remember to consult a local specialist.

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