Gordon Johnson, Extension Ag Agent, Kent Co.; gcjohn@udel.edu
Each year there is more acreage of annual plasticulture system strawberries planted in Delaware. New plantings will go in again this September. One critical practice is fumigation. I recently came across a very good article on fumigation alternatives in strawberries with the loss of methyl bromide looming. The information is from the North Carolina Pest News:
Choosing Alternatives to Methyl Bromide for Strawberries
From: Rob Welker, Department of Plant Pathology, Katie Jennings, Department of Horticultural Science, and Frank Louws, Department of Plant Pathology in the June 27, 2008 edition of the North Carolina Pest News http://ipm.ncsu.edu/current_ipm/08PestNews/08News12/pestnews.html#title3.
After many years of discussing the end of methyl bromide, we are nearing the actual end of methyl bromide for use in crops. Shortages will occur, and cost is going to be a factor as demand for the limited supply drives up the price. If you have not tried alternative fumigants on your farm, this is the time to seriously think about why you fumigate and switch a portion of your production to an alternative. The opportunity to test an alternative on a portion of your crop on your farm before being forced to use something is running out.
If you use a good crop rotation, or are moving onto new production land, then the need to fumigate is minimal. It might not even be needed at all. For many growers, though, rotations are not practical, and the same crop has been on the same fields for years, making fumigation the answer to reduce pathogens and weeds.
How can you make a good decision about what to use? Think about why you fumigate on your farm. What are the soil issues that make fumigation desirable? If you are unsure of your problems and have been fumigating simply because it is part of the plasticulture system, then try leaving some of your production unfumigated and see what the results are. You might be surprised. For most cases, however, we have seen approximately 20 percent reduction in yield when strawberries have not been fumigated. So what should you use? Rate your production field for the four problems in the chart below using a 0 to 5 scale, where 0 is not a problem at all, and 5 is a problem that will cause significant yield loss if not controlled. If you marked 3 or higher for a problem, then it should be treated with fumigation; 2 or lower can be managed in a different manner.
| No Problem to Huge Problem | ||||||
| Fungal Disease 1 |
0 |
1 |
2 |
3 |
4 |
5 |
| Nematodes |
0 |
1 |
2 |
3 |
4 |
5 |
| Annual and Biennial Weeds |
0 |
1 |
2 |
3 |
4 |
5 |
| Perennial Nutsedge (yellow and purple) |
0 |
1 |
2 |
3 |
4 |
5 |
1 e.g., Black Root Rot Complex; Phytophthora crown rot
What is currently labeled for use that might be used for your pest problems? Use the chart below to find a product or combination of products that treats the problems rated at 3 or higher.
| Fumigants |
Fungal Disease |
Nematodes |
Annual/biennial weeds1 |
Perennial Nutsedge |
| Chloropicrin |
E |
N |
N |
N |
| Metam Sodium2 (MS) |
F to G |
P to F |
G to E |
F |
| Chloropicrin + MS |
E |
P to F |
G to E |
G to E or |
| Telone C-35 |
E |
E |
P to F |
P |
| Telone C-35 + VIF3 |
E |
E |
G to E |
P to F |
| PicClor 60 |
E |
E |
P to F |
P |
| PicClor 60 + VIF |
E |
E |
G to E |
P to F |
| MIDAS + VIF |
E |
E |
G to E |
G to E |
| Paladin4 + VIF |
E |
E |
G to E |
G to E |
| Herbicides6 |
|
|
|
|
| Goal herbicide (under plastic) |
|
|
G to E |
N |
| Stinger herbicide (very specific weed spectrum) |
|
|
G to E |
N |
| Chateau herbicide (under plastic) |
|
|
G to E |
N |
1 Limited data is available on control of annual and biennial weeds by these fumigants.
2 Vapam, Sectagon or other registered formulations.
3 VIF refers to Virtually Impenetrable Film which allows lower fumigant application rates but at the same time has improved efficacy of fumigants.
4 Paladin is a new fumigant currently being used under an experimental use permit in North Carolina, Georgia and Florida and could potentially be available soon on the open market.
5 When applied in the spring control is Good to Excellent, however when applied in the fall control is reduced because the fumigant gasses off due to the warm soils.
6 See respective labels to determine the specific weeds each herbicide controls.
Key:
E = excellent control, 90% or better
G = good control, 80% to 90%
F = fair control, 50% to 80%
P = poor control, 25% to 50%
N = no control, less than 25%