Cheat Grass activity

Evaluation of TFMS Herbicidal Activity. The herbicidal potency of the 15 substituted TFMS compounds was rated after a 21-day test period on a 0-100% kill scale. Herbicidal test data were collected for two grass species (Foxtail, Cheat Grass) and a broadleaf weed (Wild Mustard) in the presence and absence of 0.1% (w/v) Tween 80. Since the tests... 

Figure 4a. Three-dimensional perspective plot of the Hansch equation describing pre-emergence activity of 4-substi-tuted TFMS herbicides on Cheat Grass (no Tween 80 present)...

As an illustration of the use of the final Hansch relationships in Table XI in explaining biological activity differences between individual TFMS series members, we will examine the activity of 4-S02CH3-TFMS and 4-C1-TFMS against Foxtail, Wild Mustard, and Cheat Grass. Table XIII gives values of the individual terms in the Hansch equations of Table XI which are appropriate to the action of each herbicide on the three weed types. At a later point, we also examine the activity of 2,4-di-Cl- and 2,4-di-F-TFMS derivatives as predicted by the Hansch relationships in Table XI. 

In general, substituents characterized by large, positive Hammett <7 constants (electron-attracting substituents) exhibit enhanced pre-emergence herbicidal activity on all weed types tested (Foxtail, Cheat Grass,... 

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