As indicated in Agrios' 3rd edition text, cotton, potato, rice, peanuts, and some small grains are the field crops receiving the most intense fungicidal control. K o is reduced by inhibiting viability or preventing spore germination or penetration of host plant. Use of protectants is enhanced by use of disease forecasting models. Therapeutics are systemic - they are taken up into host tissue through root or foliar application. Therapeutics have eradicant activity - they kill the pathogen.
Therapeutics are synthentic organics and have a narrow spectrum of activity.
Systemic fungicides are taken up through the foliage and roots. They are translocated upward through the xylem, but rarely transported down through phloem. They are not reexported to new growth. Systemic fungicides are represented by both protectants and therapeutics. Generally, they are applied as a seed treatment or in-furrow treatment as soil drench.