Organic crop variety selection
Organic farmers must rely heavily on crop competition to manage weeds. Selecting the most weed-competitive crops and varieties can make a big difference in yields.
This is a good time of year to observe how competitive your varieties are. If we all had extra time during seeding, we would plant several varieties of each crop and evaluate their competitive traits. But this is time consuming and requires special equipment, knowledge and skill to get accurate information.
Luckily, some of this work has already been done and the results can be directly applied to organic farms. With a few exceptions, it is just common sense.
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The faster, more aggressive growing, taller, leafier plants are more competitive with weeds.
An issue of concern to organic farmers is that plant breeding is likely producing varieties that only produce well with herbicides and fertilizers in relatively weed-free production systems.
A test of 250 wheat varieties in Australia showed old standard varieties released between 1880 and 1950 suppressed weeds more than most of the current varieties. Yield differences in weedy conditions were not seen when herbicides were used.
For most organic growers pondering which varieties to grow, this is a problem. If we only develop cultivars under weed-free situations, then we are missing some key information about competitive characteristics under weedier, organic and lower input systems.
Considering the cost-price squeeze all farmers face, most should be interested in information about selecting cultivars that will help them reduce input costs.
I don’t want to oversimplify this issue because crop and variety competitiveness are complex issues. A lot depends upon your location and environmental conditions.
Other factors
Seeding rates and soil fertility will also influence competitive characteristics.
Other requirements also need to be met, such as disease and insect resistance, quality, marketability, harvestability and whether there is any opportunity to use mechanical weed control methods before and after emergence.
But the important message is that any farmer can select crops and varieties that will help in managing weeds.
Selecting high quality seed can give you better seedling vigor. There is some relationship between seed size and seedling size. So having well graded seeds of larger than average size will likely give you a crop that starts faster.
Increasing seeding rates can make most crops more competitive. This is especially true of the less competitive ones.
Narrower row spacing and plant spacing can also produce more competitive crops. Having a crop that covers the ground and leaves little space for weeds is the goal.
Because every farm is different, I suggest you do your own research and selection. But here is some basic information that I use in my selection process:
- Fall rye and winter wheat are the most competitive crops.
- Barley, oats and spring wheat are generally competitive as well, but I am looking more for market quality requirements.
- Canola and mustard are slow to start but once established, are hardy competitors.
- Peas can be competitive if you select the right varieties. I have grown Princess, Victoria and Grande. Grande and Victoria are leafy and long vined, making them quite competitive.
- Flax and lentils are generally poor competitors. But even within lentils there are some differences in competitive characteristics. I grow Laird which is taller and the seed size is larger, making volunteer wheat and small stones easier to clean out.
- Biennial and perennial forages are some of the most competitive crops available and will help reduce some perennial weed problems.
