4 GENERAL SUGGESTIONS 



SELECTING THE BEST METHOD 



Local conditions must help decide which is the best method for 

 use on a particular weed problem. The kind of plant or plants, 

 extent of infestation, depth and controllability of water, accessi- 

 bility, and similar factors, need to be weighed against costs and 

 merits of the various methods that can be used. 



If local water supplies and water-control structures are suffi- 

 ciently adaptable, adjustment of water levels often controls weeds 

 and results in an abundance of desirable plants. Disking, mowing, 

 or crushing provide satisfactory control of many weeds in marshes 

 that can support mechanical equipment. Pulling by hand, mowing 

 with a sickle, or spot treatment with herbicides are often practical 

 for elimination of small patches of weeds. Combinations of meth- 

 ods sometimes prove particularly effective. These include mow- 

 ing followed by flooding, burning and spraying, spraying and flood- 

 ing, or use of two different chemicals. More detailed comments 

 on various control procedures are given in the chapter on Methods 

 (page 6). 



BEST SEASON FOR TREATMENT 



Most marsh plants have a particular growth stage during which 

 control measures are likely to be especially effective — ^the vulner- 

 able stage. Frequently, though not always, the ideal time for treat- 

 ment is associated with the plant's flowering or fruiting, probably 

 because of depleted food reserves. Needlerush appears most sus- 

 ceptible in the spring during its flowering. Mowing of cattails at 

 two particular stages of growth yields a 95% to 100% kill, whereas 

 numerous mowings at various times may result in little or no real 

 control (see page 22). 



In some plants, the ideal time for treatment shows no clear rela- 

 tion to the flowering or fruiting stages. Woody plants commonly 

 respond best when control measures are applied in later summer or 

 fall ; giant cutgrass is killed most readily about two months after 

 its flowering, during the period of maximum runner growth. Much 

 remains to be learned about the ideal time for treatment of different 

 species by different methods, and as more information is obtained 

 on these matters control programs will improve in efficiency and 

 economy. 



