Hurricane Irma ripped through Florida taking homes, trees, power lines and lives. It also took plastic from 15,000 acres of vegetable fields and wiped out more than 4,500 acres of recently planted tomatoes and other crops in addition to destroying greenhouses and other agricultural structures. Farmers are beginning to replace plastic and replant, and because of the storm, may see some differences in disease pressure this season.
One reason is that many growers are, out of necessity, skipping fumigation before planting. The need to get crops in the ground is urgent, and the time needed to fumigate and wait the required time interval is too great. In addition, for a fumigant to work well, the soil needs to be fairly dry and friable. An additional factor is there may be a delay in actually scheduling the specialists who apply the fumigants.
One disease growers should anticipate seeing more of this year is bacterial spot, especially on tomatoes, says Marsha Martin, product development manager for DuPont Crop Protection.
“Because of all the windblown sand and rain, tomatoes that did survive have damaged foliage,” Martin says. “Wounding creates openings for infection, and there is always some inoculum in the field. In addition, the transplants are coming in with some disease. They weathered the storm in greenhouses that lost their covers, so were susceptible to damaged foliage and infections from bacterial inoculum moved by wind and rain.”
Low levels of bacterial spot are already being seen in southern Florida on tomatoes. The widespread use of resistant bell pepper varieties has proved valuable, and it has not been much of a problem with that crop so far,” Martin says.
There are a number of products that are effective in controlling bacterial spot, and using them in rotation should provide good control, she says. But sanitation is important as well. Workers and equipment should be kept out of the fields when foliage is wet, because the bacteria is easily spread.
Pythium is Predicted
Experts are anticipating that Pythium will be the key damping off pathogen this season.
“Root rot will also likely be a problem,” Martin says. “Rhizoctonia is also likely to be a problem in many crops, but perhaps more significantly in beans. If farmers have skipped fumigation, it’s important to use other methods of control. These are true soil diseases and need to be treated with drip or a directed spray that can get irrigated down into soil profile if nothing was done at planting.”
Southern Blight Expected
Martin also predicts southern blight will be a particular problem this year, and it is already showing up in southern Florida at levels higher than usual for fall.
“Southern blight spreads across the surface of the soil and attacks the crown of the plant,” she says. Since much of the post-hurricane planting is without a fumigant, it’s wise to do an in-furrow or incorporated application of a fungicide at planting. You can also do one or two directed sprays of a product such as Fontelis and irrigate it in.”