Q: Can Roundup be used on weeds between rows of corn? The plants are six feet tall.

A: You may not be able to see it but most garden sprayers deliver heavy droplets that can be seen with the naked eye and mist droplets that are much harder to spot. Unless the air is completely still, the unseen mist droplets can be deposited on nearby plants, possibly killing them. Your best bet is to make a nozzle guard from a bottomless milk jug. Use tape to secure the neck of the jug to your sprayer nozzle. Walk slowly as you spray and keep the bottom of the guard/jug as close to the weeds as you can.