There are a few considerations regarding spraying and its effects upon plants and fruit, that it seems important to bring before the people of the state, notwithstanding their familiarity to many readers, and the fact that most of the matter to be presented has often been repeated in various publications, and much of it in one form or another in previous bulletins of this station. The fact that this bulletin may be read by several thousand people who do not have access to previous bulletins of the station is, perhaps, sufficient reason why the repetition is justified.
There is no question that spraying with too strong preparations of the arsenical poisons and also with kerosene emulsion will injure plant life, and certain plants are much more susceptible to their influence than others. The injury here referred to is that which becomes observable within a few days after application and which becomes apparent from spotting, withering and falling of the leaves. It is asserted by some, however, that even where there is no immediate injury, that the poison is absorbed by the tissues of the plant, a slow poisoning is induced and the leaves fall earlier than they should, and that in a year or two the tree or vine may die. The experience with spraying has now extended over many years, and if this were true in any large degree, we certainly should have abundant evidence of it ere this, and it does not seem reasonable to oppose spraying on this ground.
"Effects of spraying on plants and fruit and notes on insects,"
Bulletin: Vol. 2
, Article 8.
Available at: https://lib.dr.iastate.edu/bulletin/vol2/iss17/8