This study compared the impact of various herbicide strategies and ground cover systems on growth of newly planted and 1-yr high density apple orchards. At two commercial sites, three replications of six groundcover treatments were manually seeded, maintained, and mowed when needed by grower cooperators. Groundcover treatments were randomly assigned to strips between tree rows in experimental units of approximately 50 ft. plots with 20-25 adjacent trees around the plot. The GC treatments were: (1) OVN mix – Orchard-vineyard-nursery composed of 40% proprietary perennial rye, 30% creeping red, 30% chewing fescue seeded at 25 lbs/acre, (2) OVN mix (same grass mix as described) seeded at 75 lbs/acre, (3) Low-Grow Mix (50% firefly hard fescue, 20% intrigue chewing fescue, 20% azure sheep fescue,10% minotaur blue hard fescue) seeded at 50 lbs/acre, (4) Low-Grow Mix (same fine leaf fescue mix as described) seeded at 100 lbs/acre, (5) Native weed vegetation as established by mowing at each site, and (6) Dutch White Clover seeded at 20 lbs/acre.
The first growing season of this project revealed the strengths and weaknesses of and variability in weed species that grew through various herbicide treatments in young, high-density apple plantings. It also proved how the lack of weed control impacts negatively on tree growth. The side-by-side treatment comparisons demonstrated how long the various residual herbicide treatments were effective, how soon a post-emergent treatment was necessary, and consequently, how often treatment was necessary through the growing season. The collaborators gained a realistic perspective of establishing ground cover between tree rows, the best timing for establishment, and how long it takes for germination for each seeding type.
There were no weed control treatments in newly planted or 1-year established orchards that lasted season long. Treatments using Matrix or Alion in the 1st year established orchard provided the longest window of control. The combinations of Chateau or Goaltender (plus Prowl or Surflan) in the newly planted orchards required only a single follow-up post-emergence treatment. Other treatments required 2 post-emergence applications. The shortest residual treatments were the Prowl or Surflan alone. The longer weed control season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 paraquat applications compared to 1 paraquat application in most of Lamont treatments with a month shorter weed control season in the newly planted orchard.
GreenMatch, the OMRI certified organic herbicide, provided the same weed control as the untreated check in newly planted orchard, and slightly better in the 1-year established orchard, but the tree growth was the same as untreated check in newly planted trees. It was difficult to keep up with applications of GreenMatch which required applications every 2 weeks or more often to control succulent germinating weeds. High rates of material and cost will deter use of GreenMatch.
Tree growth in the untreated checks was reduced compared to herbicide treatments. There was a greater negative impact on tree growth in the newly planted orchard than the 1- year established orchard.
This study showed that two grass mixes can establish and compete with weeds differently when monitored from May 2011 until June 2012. The Orchard-vineyard-nursery(OVN)-mix of rye and fescues treatment (regardless of the two rates tested at the sites) grew taller and a little more thicker than the low-grow mix of fine fescues. The OVN-mix(if managed individually) needed to be mowed more frequently (it was always taller than the low-grow mix) and did not establish much better than a low-grow mix one year after seeding. Interestingly, the clover treatment (at both GC sites) showed to be a good alternative for groundcover management. It established and competed even better than the two GC grass mixes studied in this project. At the beginning of the second season and after repeated freeze events in 2012 (this measured only at the GC Lamont site), the low-grow mix of fine fescues was still less dense and did not compete better against weeds than the OVN-mix. There is a need to continue evaluating the low-grow mix (and also the clover plots) as it grows and establishes very slowly compared with the OVN-mix under Northeastern conditions. An acceptable low-grow mix establishment free of weeds by the end of the second year and a potentially less demanding ground cover option for mowing may save time, production costs, and be more appropriate to NY fruit growers.
1) show strengths and weaknesses in side-by-side herbicide treatments in young plantings
2) identify the pros and cons of various ground cover seeding options
3) evaluate herbicide treatments for trunk damage from glyphosate use
4) evaluate changes in soil health properties