Experimenting can be pretty costly. About five years ago there was some discussion about various daffodil growers who had come up with a weak solution of Round-up (Glyphosate) that could be sprayed right over the tops of the daffodils as they were emerging from the ground that would kill all of the winter weeds but NOT harm the daffodils. The discussion moved off list and in talking with Ted Snazelle he basically said that ANY Round-up getting into the daffodils WOULD be HARMFUL.
Again off list it was appearing that some of these guys had come up with the miracle cure for weeds in field grown daffodils. I waited an extra year as this experiment moved along and then I went and duplicated what they were doing on a wide scale only I went and spot sprayed most of my larger, thicker drifts of daffodils and weeds just as they were doing over whole weedy sections of their fields.
Notice the hole in this drift of Laurens Koster from this experiment. The first year it appeared that only the weeds were killed as the daffodils died down normally with NO weeds in this spot. The second or third year the daffodils looked pretty sick in the spring in these spots all over my fields. Then the third or fourth year few to no bulbs survived and five years later there are still spots with some of the jonquil varieties where the bulbs survived but are really not recuperating. Anyway one of the gentlemen called up all in a panic during his third year admitting that he had killed over an acre of his daffodil field….He asked if I had also sprayed all of my fields!!!!
The soil PH averages right at a 7 in this whole field and N-P-K actually tests a little low for all of them especially nitrogen. Notice the amount of organic mulch spread on the ground. We dug the rows on each side last year and will rogue out the strays this year and begin to replant this section in a couple of years if I get all of these bulbs out of here this year. We use a lot of tree chips that are fresh and these slowly break down and will tie up excess nitrogen floating around in the soil. Releasing it more slowly over several years as microbes die and release the nitrogen they have harvested. Keith Kridler Mt. Pleasant, Texas