One of the most commonly-grown annual crops in BC is sweet corn. Producers probably see this as a simple crop, at which some summer cash can be easily made. Many first-time corn growers probably find themselves surprised, however, to discover sweet corn can sometimes be far from simple. Based on an article in a recent edition of Top Crop Manager*, we summarize here some factors to keep in mind when growing sweet corn.
Optimize Plant Population
What point is there in spending money on crop inputs, without planting the maximum number of corn plants per acre? The more plants grown, the more marketable cobs you will produce. But, too many is detrimental. For sweet corn, a common row spacing is 30 inches between rows, and the maximum plant population is about 21,000 to 26,000 plants per acre, based on the BCMA guidelines of in-row plant spacing of 8 – 10 inches.
Nutrition
As for all crops, get a soil test done well ahead of time. It should go without saying that you can save money by applying only what you need.
pH is as critical for an annual vegetable crop as for perennial berry crops. When your soil acidity is not in an optimum range, some of the fertilizer you spend money on will be wasted.
If you have a lack of potash or magnesium, these nutrients can be applied well ahead of planting and disced in. These nutrients don’t leach as much as, say, nitrogen.
At planting time, a starter fertilizer with phosphate is the most efficient way to apply this nutrient. It is usually accompanied by a little nitrogen, as well as zinc and boron.
If necessary, side-dress nitrogen before the knee-high stage.
Stand Establishment
An early stand means high vigour. Unless you are planning on using floating row covers, do yourself a favour and don’t plant too early. If you do, you risk the emergence of weak plants, which are more prone to root and crown pathogens. The minimum soil temperature should be no less than 10 degrees C. Plant seed no deeper than 1.5 inches.
Weed Control
We separated weed control out from Stand Establishment, for a good reason. In our experience, way too many producers try to skimp on weed control. Corn that is competed by weeds when the corn is young will not recover to produce a maximum crop. When weeds get past 4 inches, your yield will be definitely reduced. Don’t let bad weather cause you to skip crucial weed control opportunities. Plan ahead. Start with pre-planting incorporated herbicides if they are available. Follow with a “plan B” pre-emergence application. Finally, get the big guns ready; you must assume you will be applying post-emergence herbicides. If necessary, do all three.
Insects
Gone are the days when we didn’t have to worry about bugs. Happily, so far, we still don’t have diseases, to speak of. But insects – different story! If you have to apply insecticides to your stand after knee-high, it is better to achieve control then worry about losing some plants by “bulldozing” with your spray rig.
Wireworm. You have to know if you will expect wireworm; there is not much excuse not to have done your homework. Rotating will make some difference. Definitely do not grow corn after corn; that is just asking for it. If you think you will have some, use Force 3G at planting.
Aphids. In sweet corn, aphids will on and off be a problem. Be ready. In a year when aphids are a problem, there are inexpensive insecticides you can use.
Western Corn Rootworm. We avoided this pest for many years, but now it is definitely here. You must plan for it. Unlike the cow corn growers, there aren’t any “stacked” hybrids with genetic protection built-in. But, ask your seed supplier if your variety has been treated at source for rootworm.
Other lepidopterans. In 2017 some growers had a problem with Armyworm. It may have been a fluke – it definitely wasn’t expected, and may have accidentally been brought in as a “hitchhiker”. In any case, until you know better, you have to, again, assume you will have to deal with it. Again, there are insecticides you can use to deal with it.
Overwhelmed? Talk to one of our friendly and knowledgeable sales team member for more information.
Reference: “Agronomy Tips for New Corn Growers”, by Bruce Barker, in Top Crop Manager, December 2017.