-5- 



When you go to diagnose a case of crop injury, be sure to look at roots as well as 

 the tops. Also take into account all the potential sources of injur)', such as her- 

 bicides, insecticides, diseases, insects, water damage, wind erosion, compaction, 

 and crusting. Be sure to get all the facts. 



MARIHUANA IDENTIFICATION 



There have been several reports of weeds that resemble marihuana, but are hairy and 

 have yellow flowers. These plants are upright cinquefoil {Potentilla recta) --not 

 marihuana {Cannabis sativa) . They both have digitately compound leaves, but 

 cinquefoil is a perennial and marihuana is an annual. 



Marihuana also has separate male and female plants (dioecious) and blooms much later 

 than cinquefoil, which is beginning to bloom now. Some of the buttercups (Ranunculus 

 spp.) are often confused with cinquefoil. They have deeply divided leaves and could 

 also be mistaken for marihuana. 



WELL SAFETY 



We have received questions about chemicals getting in wells. The most-frequent 

 causes are the flushing or overflowing of sprayers near wells or the siphoning of 

 hoses while filling sprayers. It would also be possible, if a loss of pressure 

 occurs, to get chemicals' from a spray tank into a muncipal water supply by siphoning. 



Prevention is cheaper and easier than the cure. Here are some suggestions: 



1. Do not leave the sprayer unattended when filling the tanks. 



2. Do not flush tanks where a chemical will drain into wells. 



3. Do not place the hose in the tank. A bracket to hold the hose and the tank will 

 prevent siphoning. The inovative handyman can probably design an anti-siphoning 

 device. 



What to do if the material gets into the well is another matter. First, determine 

 the use of the well. Is the water used for human or animal consumption? Is the 

 well used to irrigate a garden? Second, determine the chemical (s) involved and 

 their toxicity. Third, start pumping the well as soon as possible, and dispose of 

 the water in a suitable manner. Some materials such as Treflan, Lasso, or 2,4-D 

 ester will be visible in water in very dilute amounts. 



READ THE LABEL' AND FOLLOW ALL PRECAUTIONS 



This weekly report was prepared as follows: 



INSECTS: H.B. Petty, Steve Moore, Roscoe Randell , Don Kuhlman , and Tim Coo ley , 

 College of Agriculture , University of Illinois at Urbana-Champaign , and the Illinois 

 Natural History Survey. 



WEEDS: M.D. McG lamer y , Department of Agronomy . 



AG COMMUNICATIONS: Del Dahl . 



The information for this report was gathered by these people, staff members, county 

 Extension advisers, and others, in cooperation with the USDA Agricultural Research 

 Service, Plant Pest Control Branch. 



