Finding the Answer to Weed Control on Organic Orchards

The two common organic weed control strategies of cultivation and mulch lack sufficiency when used solely. However, when combined with the use of herbicides, they function fairly well, according to new research. 

Greg Peck, assistant professor in the School of Integrative Plant Science, Horticulture Section at Cornell University, shared his research findings of a 4-year study performed at the Cornell Orchards. His research was conducted with help of graduate student Kate Brown. The study was shared on June 1 in an article for Growing Produce. 

The experiment was conducted to identify effective organic weed control options for apple growers. Peck purposefully chose to study relatively weak trees, the ‘Honeycrisp Firestorm’ trees on Bud.9 rootstock. Their trial consisted of 12 different weed treatments and choosing weak trees allowed them to examine the strength of the weeds.  

Conclusions of the experiment indicate that a combination of weed controls, specifically wood-chip mulch and organic herbicides, work best. “He suggests using mulch plus herbicide in the early establishment years (1-4) and switching to cultivation in later years”. 

The experiment led to additional findings. Results showed that the sole use of mulch treatment increased the quality of the soil. Cultivation in addition to herbicides grew the largest trees, and mowing showed the same results as no weed control whatsoever. Peck also offers several suggestions to organic orchard growers which include early-season weed control, hoeing when perennial weeds become established, using more vigorous rootstocks, taking leaf samples, and choosing slow-growing cover crops. 

Read more about the experiment and findings on Growing Produce.