Outlook for 2021 maize harvest

Following a couple of bumper maize growing years, it is looking likely that maize crop yields this season will be more typical,
if not slightly lower, than usual and we could see a split in harvest dates due to there being two distinct drilling periods this year.
If we compare crop heights in June and July last year to this year, as the images below highlight,
some crops are much further behind now compared to last year.
This could mean a considerably later harvest, even into the end of October/November.
There is also the possibility of some crops struggling to reach maturity before the cold weather sets in this year.
If harvest is delayed, the weather may impact operations and the quality of the crop to a great extent.

Cold weather at harvest​

As a tropical grass species, maize is very susceptible to frost. If maize goes through a hard frost,
it changes the physiology of the plant and all vegetative growth stops. If you get a cold spell in the run up to harvest,
you will need to take the maize off as soon as possible to ensure you get the best quality forage possible as the plant will quickly deteriorate after this point.

Is your crop ready to harvest?​

As maize is likely to be lower yielding this year it’s important to harvest it at the optimum time to make the best use of the available crop.
It is also worth noting that depending on the conditions for the rest of the season, we could see crops mature rapidly.
Therefore, don’t assume that because the crop went into the ground late that harvest will be delayed, assess the crop often so you don’t miss the optimum timing.
I recommend walking the crop as regularly as possible to check what stage it is at. Make sure to walk out into the crop, rather than simply driving by the field.
As a rule of thumb, maize will dry off at 1% per week from August and the aim is to reach a DM of at least 30% for high quality silage.
There are a number of physical indicators to look out for to help achieve this level.

1. LEAVES – Check the bottom leaves of the plant, when the crop is ready, they will start to go brown. It is important to note that this assessment is not appropriate if you are growing a ‘stay green’ variety.
2. STEM – Take the maize stem and twist until moisture starts to drip out of it, this usually takes four twists. If more than 4-5 drops are released, then the crop is too wet. If you see 1-2 drops then it is ready. If no water drips out, cut as soon as possible.
3. COBS – Break the cob in half and look at the milk line on the kernel. This line shows the point where it turns from sugary juice to starch. When the milk line is two thirds of the way down the kernel towards the centre of the cob, the cob DM is at the right point for harvest.

Watch out for corn borer​

Corn borer parasite
There have been reports of the corn borer parasite in some maize crops in the Southeast of England.
There is no treatment available for this parasite, and it can be extremely damaging to maize crops.
If you spot this in your crop, speak to your agronomist to see how it can be controlled via crop rotations.