what is the major problem with aphids
The lettuce aphid is a problem worldwide and has recently become problematic in the western United States and Canada (Liu and McCreight 2006; McCreight 2008). However, the first three species of aphids listed above are most economically damaging in Florida (Nuessly and Webb 2010). Although heavy aphid pressure can stunt plants, the major problem aphids cause is head contamination, which makes lettuce unmarketable.