WTOTER MEED CONTROL IN STRAWBERRIES 



The control of weeds, especially chickweed in strnv/berry fields during the 

 fall and winter, continues to be a vexing problem. Numerous materials have been 

 tried but very few recommended. All are far from ideal. Therefore the serious- 

 ness of the problem demands that growers be informed of the best solution available. 



IPC was one of the first materials to give some promise for fall and winter 

 weed control in strawberries. If used according to directions, it was pretty 

 safe on the strawberries, but not very effective against chickweed. At present 

 it is offered for sale on the West Coast only and is not readily available. 



Some of the dinitros have been recommended for this purpose. Under the right 

 conditions a dinitro can be effective. Unfortunately, the right conditions are 

 hard to fulfill in our climate. The dinitros owe their effectiveness to their 

 ability to kill by contact the cells in the tops of plants, their so-called "burning" 

 action. They will "burn" the leaves of strawberry plants as well as those of weeds. 

 After strawberry plants are dormant, this "burning" of the leaves causes no permanent 

 injury to the strawberry plants provided the spraying is properly done so that the 

 plant crowns are not soaked with spray. 



The dinitros are much more effective at high temperatures than at low. Early 

 applications would be desirable but severe injury to the strawberries would probably 

 result from an application made before dormancy is complete. One can not be sure 

 of strawberry plants being dormant before mid or late November. At that time of 

 year, warm sunny days which are necessary for best results with DH seldom occur. 



Since a DN kills by contact, the weeds to be killed must be thoroughly wetted 

 with the spray. With small chickweed this is no problem but by the time a DN can 

 be used safely, chickweed has often grovm into a thick dense mat. Only the surface 

 of this mat is reached by the spray and results are unsatisfactory. 



Use no more than one pound of actual DN in 40-100 gallons of water per acre. 

 Read the directions on the container for the amount to give one pound. 



The most effective material for chickweed control has been chloro IPC, often 

 called simply CIPC. It is much more effective and certain for this purpose than 

 either IPC or DNs. It has been quite damaging to strawberry plants where improper- 

 ly handled. 



About 1954 we started recommending the use of CIPC. In the summer of 1956 

 reports were received that severe injury to strawberries had occurred in New Jersey 

 and Michigan, in some cases so severe that 100 per cent of the plants were killed. 

 Consequently, we sent out a warning in FRUIT NOTES to refrain from the use of CIPC 

 until the cause of the trouble was learned. It has since become apparent that the 

 trouble was caused by careless application. The chemical was applied before the 

 plants v^fere fully dormant or too much of the chemical was applied. This is very 

 definitely a case where a little is good; more is NOT better. 



Chloro IPC should not be used in excess of one pound per acre in enough water 

 (40-100 gallons is usually enough) to spread it evenly over a full acre, 43,560 

 square feet. If the area sprayed is less than this, reduce the amount of CIPC 

 accordingly. For example: An acre of strawberries is to be sprayed. The rows 



