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Question from a Brit here and wondering if any of you have any other thoughts.
When we plant in the Autumn we so no affects from glyphosate for the germinating seedlings in a no till situation.
When we plant in the Spring we see ocassional ill effects of germination.
This seems to happen when we have a bit more residue and that it is a bit colder.
My friend has come up with this conclusion - what do you think:
Glyphosate causes the production of acids around the decaying roots of the sprayed off plants. We think this makes the area very acidic for the germinating plants if the roundup has been used too soon before drilling. This tends to occur only at lower temperatures for the soil so for example when we get cool springs (remember we don't warm up as much as USA in general) germination can be hampered. You only get this negative affect in no till and it seems to be worse for smaller seeds ie cereals rather than larger ones ie beans. Canola may be less affected because its virtually on the surface.
I know plenty of people spray one day and seed the next (eg new zealand does a lot of it with brassicas into pasture) but we're wondering if its because usually the soil temperature is warm enough by then to nullify the acetic acid affect which we think we see. So the balance between spraying too early in the winter and too late in the spring for the spring cropping is tricky - too early(ie before xmas) and in our climate you risk regrowth of weeds hard to control in crop, too late and you risk the acid decaying affect for the next crop (ie less than 4-5 weeks)
Where farmers use higher disturbance direct drills we think the affect is less noticeable if at all and that is because it seems the acid concentration is not much more than 15mm away from the decaying roots.
We think maybe if we used something like pelleted lime down the spout near the seed we could nullify the acid zone a little to help the plant seedling?
This is not an issue in every situation but it crops up now and again, as it happens this spring is quite warm and so the affect is not so noticeable.
Has America got any comments about it? :) What is happening to the plant when gly is applied and why do you think we see differences according to the time of year? Any other good ways of managing it - p.s. remember we're not corn and soybean country - its mainly winter and spring wheats and barleys, canola and field beans.
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Glyphosate and germination
