Safe to spray after seeding?

[RobbieH]

I used my atv drag to turn over some ground in a small plot of mine. I then seeded a brassica mix. I wish I had time to get out there a couple weeks ago to spray first, but I didnt, and I really wanted to get the seeds in.
So I seeded yesterday and was thinking about spraying the existing weeds today. Would the spray (gly) hurt the seeds?

 

[catscratch]

Gly won't hurt the seed. Anything not sprouted should be fine.

 

[bigbluetruck]

No as long as things aren't sprouted, youll be fine, BUT it will kill the germ on any seeds that aren't covered with dirt

 

[X-farmerdan]

Most of us assume it's ok to seed today and spray tomorrow....or seed today and spray today. And, most of the time most of us would be correct. It's an interesting topic. I read. Therefore, I do. What I came away with are a couple of points. Based on what I remember, research doesn't always address the effect of gly on all type of seeds. The results for what you plant may be different than the research findings which is surprisingly limited. What I came away with is this - until a seed absorbs water in the amount of 30% of it's dry weight, spraying gly on seeds has no impact on germination percentage. After that, germination goes down hill quickly.

As an aside and somewhat related to this is the amount of water a seed needs to start the germination process.
This is from Corn & Soybean Digest:

The critical soil moisture for seed germination to occur is 30% for corn and 50% for soybeans(Copeland). The following is a quick way to estimate soil moisture for clay, clay loam, silty clay loam, sandy clay loam, loam or silt loam soils. At 25-50% soil moisture, a ball of soil formed with the hand will feel slightly moist, form a weak ball when gripped in hand, but it won’t leave dirt stains on your hand like wetter soil would, and few aggregates would break off of the ball.(USDA)


Seed-to-soil contact is critical for imbibition to take place. Imbibition is uptake of water into the seed. When a seed swells with water this is not an indicator of seed viability because even dead seed will imbibe water in the same manner as live seed. Soybeans will imbibe two to five times their weight in water while corn only 1.5 to two times its weight.

You can make your own inferences from there.