Canadá: Can potatoes be grown without chemicals?
Potatoes typically require fungicides and pesticides but with the correct rotations and lots of ladybugs, it is possible.

At least one organic farmer has figured out how to grow potatoes without the usual weekly dose of chemicals.
It’s a myth that potatoes demand synthetic protection, says Brent Harris of Fraserland Organic Farms in Delta, B.C.
He said a healthy potato crop can be grown once the land has been in an organic system long enough.
“Rotation plays an important role. We’d have problems if we grew potatoes on potatoes or potatoes every second year,” Harris told the Prairie Organics Conference in Winnipeg in late February.
He said his farm normally keeps a four year buffer between potato crops, which isn’t hard to do, considering the wide variety of organic crops it grows.
“We don’t irrigate unless we absolutely need to. When a potato crop gets too moist, that’s when you get your fungus problems. The crop is healthier if we error on the side of too little water rather than too much,” he said.
“Some of the land has tile drainage, and that helps. We’d prefer to have tile drainage on every field, but it’s expensive. There are some bio-pesticides and natural products we have in our toolbox, but they’re very limited. Rotation and managing moisture are the two main management tools.”
Harris said he is picky about which varieties to grow, to the extent that he conducts his own on-farm trials using varieties bred with disease-resistant traits. The farm grows red, white, yellow flesh, purple, russet and baby nugget potatoes.
The hardier disease-resistant varieties don’t yield as high, but that’s the tradeoff an organic farmer has to live with.
“Weeds aren’t a big issue in organic potatoes,” he said.
“You can go in there and cultivate them.”
Harris said biodiversity goes hand-in-hand with organic crop production. It happens over time whether it’s intentional or not. Beneficial insects are the most significant, as he explains on the Fraserland website.
“Years of organic production have helped us to build an ecosystem friendly to ladybugs and bees and other beneficial insects. A strong ladybug population can mean the difference between a successful field of peas and a disaster crop destroyed by aphids.”
Consumer demand for high quality products has prompted the farm to cull 25 percent of its potatoes before bagging for the market. Its high standards remove potatoes that don’t meet Canada No. 1 grade.
Spuds with minor skin defects, unique shapes and odd sizes may be ugly, but they’re still plenty good to eat.
Enter the Pugly Potato. These No. 2. spuds make a bold statement that ugly is only skin deep. Plus, they are sold at an attractive price compared to No 1. Harris said his Pugly Potatoes are designed to help change the way we think about produce.
Fuente: http://www.producer.com/2016/03/can-potatoes-be-grown-without-chemicals/