Submitted to: Southern Nursery Association Research Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/6/2005
Publication Date: 12/1/2005
Citation: Richardson, B.M., Wehtje, G.R., Gilliam, C.H., Fain, G.B. 2005. A non-chemical alternative for weed control in container nursery crops. Southern Nursery Association Research Conference 50: 446-449. Interpretive Summary: Preemergence herbicides may be impractical for growers that are producing crops in large containers and the labor involved in hand weeding is becoming very expensive therefore, growers are seeking alternatives. Pine bark nuggets have been used as mulch in landscape beds for many years to control weeds. This research shows that it can also be used as mulch in container nursery crops to control weeds.
Technical Abstract: Container nursery crops are among the most valuable crops produced in the southeast. Weeds can reduce the value of nursery crops by reducing crop growth through competitive effects and reduced salability due to consumer demand for weed free crops. Growers primarily use hand weeding and preemergence herbicides as methods of weed control. However demand has increased for larger container crops and preemergence herbicides are impractical due to the increased area needed to grow a crop in a large container. Hand weeding is another option but expensive and labor costs continue to increase. Crapemyrtle (Lagerstromia indica ‘Acoma’) were transplanted from trade gallon containers into 7 gallon containers. All plants were potted to equal depths, approximately 3 inches below the top of the container. Three treatments consisted of broadcasting 25 bittercress (Cardamine hirsuta) seed on the surface of the substrate of each container, then coarse pine bark nugget mulch was hand applied at 0, 1.5 and 3 inches respectively. Two other treatments consisted of first applying mulch at 1.5 or 3 inches, then broadcasting the bittercress seeds on top of the mulch. These studies show that pine bark mulch can provide effective weed control for nursery crops grown in large containers. At 180 DAT oxalis was present in the no mulch, no herbicide treatment which contained 3.9 weeds, averaged 35 % coverage of container surface and averaged a shoot dry weight of 12.9g per container. All other treatments produced insignificant oxalis. At 180 days after treatment (DAT) bittercress was present in the no mulch-no herbicide treatment which averaged 8.1 weeds, 100% coverage of container surface and a weed top dry weight of 59.6 g per container. The treatment of no herbicide,1.5 inches mulch with seeding coming after the mulch averaged 2.6 weeds, 44% coverage of container surface and 33.7 g per container. Both treatments were significantly different from each other and both were significantly different from all other treatments. Growth crapemyrtle and gardenia was not affected by any treatment at 180 DAT.