Integrating ground cover crops and new herbicide strategies (conventional and organic) for tree growth and soil health

Integrating ground cover crops and new herbicide strategies (conventional and organic) for tree growth and soil health

Summary

The first growing season of this project showed the collaborators the realistic perspective of establishing ground cover options, the best timing for establishment, and how long it takes for germination.
We also learned about the variability in weed species that grow through herbicide treatments in the rows and how intensive hericide plot management can be when the post-emergence treatments are applied at different timings.

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, and the some of the combinations with Chateau (Prowl or Surflan) and Goaltender (plus Prowl or Surflan) in the newly planted orchards required only a single follow-up post-emergence treatment. Other required 2 post-emergence applications. The shortest residual treatments were the Prowl or Surflan alone. The longer season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 Gramoxone applications compared to 1 Gramoxone application in most of Lamont treatments.

GreenMatch, the OMRI certified organic herbicide, provided the same weed control as the untreated check in newly planted orchard, and slightly better in the 1styear 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. But there was a bigger impact on tree growth in the newly planted orchard than the 1st year established orchard.

Objectives/Performance Targets

Short term:
1) identify the pros and cons of various ground cover seeding options
2) show strengths and weaknesses in side-by-side herbicide treatments in young plantings
Long term:
3) evaluate herbicide treatments for trunk damage from glyphosate use
4) evaluate changes in soil health properties

Accomplishments/Milestones

Two ground cover trials were partially established this year. The Mason GC and the Lamont GC trials were seeded on June 9 and August 15, respectively. At both sites, three replications of six ground covers treatments were manually seeded, maintained, and mowed when needed by grower cooperators. The Mason GC trial was mowed on August 4, 22, Sept.28, and Nov 15. The Lamont GC trial was mowed only one time at the end of the growing season on Nov. 18. Percentage cover of sod row middles and weed composition were evaluated on August 22 at the Mason GC site and on Sept. 30 and October 6 at the Lamont GC site. This year was a challenging season weather-wise. Apparently, the Mason ground cover plots were more affected by an early and severe summer drought than the Lamont ground cover plots which were seeded after the hot weather. GC plots were not well established at the Mason site. Temperatures were unseasonably warm in Western NY with over 15 days at 90°F or above during the June and July months.

The Lamont Fruit Farm orchard was planted on May 12. Herbicide applications had to wait for a window for treatment after soil settled and applicators could walk on open ground after the heavy rains. The residual herbicides were applied May 23. There was 3.5 in. rain the first 30 days after the application, and 7.2 in. of rain over the 3 month period after residual herbicides were applied. This orchard also had trickle irrigation installed and was operating during the month of July when there was no precipitation.

The Mason Farms orchard was planted in 2010, herbicide test plots were established and pre-emergence treatments were applied April 22 followed by nearly 6 in. of rain the following 30 days and total of 10 in. of rain for the 3.5 month period after the residual herbicides were applied. Before the residual applications, this orchard had a carpet of winter annual weeds mainly annual bluegrass (Poa annua) and hairy bittercress (Cardamine hirsuta).

Herbicide treatments were applied with a CO2 R & D sprayer using 2 L bottles for each treatment using a single Spraying Systems 8004 110o EVS nozzle, .28 gallons per minute at 30 psi, at 2 mph resulting in 34 gpa at Lamont’s and 23 gpa at Mason’s. Herbicide strips in rows at Lamont’s were 2 ft wide, and at Mason’s, 3 feet.

Percent weed cover was evaluated at least 2-3 week intervals and when weed cover reached a threshold of 20-30%, post-emergence treatments were made using paraquat in most plots or glyphosate in 2 treatments. The tables below show the number of days the residual was effective before the first paraquat application was needed (DAT). Statistical analysis was conducted using Anova, and Tukey HSD mean separation, to look for differences in weed control on each data sampled.

Herbicide Treatments in New and 1 Year Established Trees
NESARE Project: Deborah Breth and Mario Miranda Sazo

Treatments, Rates and Timings – Lamont Fruit Farm

Untreated control – handweeded on Aug. 18
Prowl H2O (4 qts./a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 2, 19
Prowl H2O (4 qts./a) @ May 23, Touchdown IQ (2 qts./a) @ Jul 2, Aug 24
Prowl H2O (4 qts./a) plus Chateau WDG (8 oz.a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 2, 19
Prowl H2O (4 qts./a) plus Chateau WDG (8 oz.a) @ May 23, Touchdown IQ (2 qts./a) @ Jul 14
Prowl H2O (4 qts./a) plus GoalTender (3 pt./a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 19
Surflan (4 qts./a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 2, 19
Surflan (3 qts./a) plus Chateau WDG (8 oz./a) @ May 23, Gramoxone Max (2 pts./a) @ Aug 24
Surflan (3 qts./a) plus GoalTender (3 pt./a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 19
Surflan (3 qts./a) plus Matrix (4 oz./a) @ May 23, Gramoxone Max (2 pts./a) @ Jul 19, Aug 24
Surflan (3 qts./a) plus Matrix (4 oz./a) plus GoalTender (3 pt./a) @ May 23, Gramoxone Max (2 pts./a) @ Aug 24
Sinbar (8 oz./a) on May 23, Gramoxone Max @ Jul 2, 19 , Aug 24
Green Match (~20 gal/a ) June 20, Jul 2, Aug 24

Treatments, Rates and Timings – Mason Farms

Untreated control – handweeded on Aug. 17
Prowl H2O (4 qts./a) @ Apr 25, Gramoxone Max (2 pts./a) @ May 25, Jul 13, Aug 17
Prowl H2O (4 qts./a) @ Apr 25, Touchdown IQ (2 qts./a) @ May 25, Jul 21
Prowl H2O (4 qts./a) plus Chateau WDG (8 oz.a) @ Apr 22, Gramoxone Max (2 pts./a) @ Jun 3, Aug 12
Prowl H2O (4 qts./a) plus Chateau WDG (8 oz.a) @ Apr 22, Touchdown IQ (2 qts./a) @ Jun 3, Aug 17
Prowl H2O (4 qts./a) plus GoalTender (3 pt./a) @ Apr 22, Gramoxone Max (2 pts./a) @ Jul 7, Aug 12
Surflan (4 qts./a) @ Apr 25, Gramoxone Max (2 pts./a) @ May 25, Jul 13, Aug 17
Surflan (3 qts./a) plus Chateau WDG (8 oz./a) @ Apr 22, Gramoxone Max (2 pts./a) @ Aug 24
Surflan (3 qts./a) plus GoalTender (3 pt./a) @ Apr 22, Gramoxone Max (2 pts./a) @ Jun 3, Aug 17
Surflan (3 qts./a) plus Matrix (4 oz./a) @ Apr 25, Gramoxone Max (2 pts./a) @ Aug 12
Surflan (3 qts./a) plus Matrix (4 oz./a) plus GoalTender (3 pt./a) @ Apr 22, Gramoxone Max (2 pts./a) @ Aug 17
Sinbar (8 oz./a) on Apr 25, Gramoxone Max @ Jul 21, Aug 17
Green Match (~20 gal/a ) Jun 3, Jun 20, Jul 7, Jul 21
Matrix (4 oz./a) on Apr 25, Gramoxone Max (2 pts/a) @ Aug 17
Alion (5 oz./a) on Apr 25, Gramoxone Max (2 pts/a) @ Jul 13
Diuron 4L (1.6 pt./a) plus simazine 4L (1 qt./a) @ Apr 25, Gramoxone Max (2 pts./a) @ Jul 7, Aug 12

Effects on tree growth were evaluated by measuring the tree caliper 12 inches above the graft union in April and after leaf fall. The trunk cross sectional area was calculated for each measurement and the % increase was calculated. Statistical analysis was conducted using Anova, and Tukey HSD mean separation.

• Herbicide Treatments, Rates, Timings

Impacts and Contributions/Outcomes

Mason GC site:
Overall ground cover emergence did not look very good and was delayed for more than a month. Plots were not irrigated before or after the ground covers were seeded as soil moisture was adequate at planting. The first rain (0.45 inches) occurred 13 days after plots were seeded. Overall maximum temperatures for the months of June, July, August, and September were 91°F, 99.5°F, 86°F, and 86°F, respectively. Total rain amounts for the months of June and July were lower than two inches. Rains increased and were 7.09 and 5.17 inches for August and September, respectively. By the end of August, the OVN-mix and the Low-Grow mix treatments did not successfully establish and were severely contaminated by summer weeds (not by fine fescues as desired). Soil coverage of fine fescues was less than five percent for both mixes.
Lamont GC site:
All ground covers grew reasonably well in 2011. Overall ground cover emergence did look pretty good for all treatments 45 days after plots were seeded. Soil moisture was adequate at the moment of planting and plots did not receive supplemental irrigation. First germination was observed with the dutch white clover seeds 9 days after plots were seeded, followed by the OVN-mix , and lastly by the Low-Grow mix. Overall maximum temperatures for the months of August, Sept., and October were 69.2°F, 63.3°F, and 50.8°F, respectively. Two months after planting, the rain measurements were two times higher than at the Mason GC site and were 3.94 and 4.41 inches, respectively. Average air temperatures were also lower and not as severe. By the end of the growing season, the low-grow mix grasses were 4-5 inches shorter than the OVN-mix grasses and both averaged a 85% or more of soil coverage. Weed pressure and composition was numerically higher and more diverse only with the untreated plots.
The Mason GC site is still in place and will be evaluated in the spring of 2012. This site won’t be terminated. A second Mason GC site will be established early in the spring of 2012 to collect missed information. It is important that this new site is well cared for (in case of a lack of precipitation) so a good establishment of ground covers is achieved for future Cornell extension activities in the east side of Rochester.

By the end of the 2011 growing season, the OVN-mix treatment (regardless of the two rates tested at the site) grew 4-5” taller and just a little more thicker than the low-grow mix of fine fescues. A low-grow mix of fine fescues may need to be mowed less times per season than the standard OVN-mix (the most common ground cover mix used by Western NY fruit growers.

The longer season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 Gramoxone applications compared to 1 Gramoxone application in most of Lamont treatments.

Percent weed cover was evaluated at least 2-3 week intervals and when weed cover reached a threshold of 20-30%, post-emergence treatments were made using paraquat in most plots or glyphosate in 2 treatments. The tables below show the number of days the residual was effective before the first paraquat application was needed (DAT).

The tables below show the first treatments to break under the rainfall were Prowl and Surflan with ragweed and foxtail the first to germinate. The higher rate used, the longer the effective residual. These herbicides have no burndown activity, so if any weeds were already germinated at the time of application, there would not be any effect. The more rainfall at Mason’s cut the period of effectiveness short compared to less rainfall at Lamont’s.

The next treatments to break were Prowl/Surflan with Chateau at 8 oz./acre. If a higher rate was used, it would have lasted longer. At Lamont’s the Surflan + Chateau lasted longer than Prowl + Chateau, but not in the Mason plots. Treatments with Chateau – PPO which has residual and post-emergence control, burned back the winter annual weeds at Mason’s but the first weeds to break through the treatments were the grasses. Note the label restrictions of Chateau for application late fall at dormant until pink bud.

The Prowl/Surflan combination with Goaltender – PPO, with pre and post emergent control (but not after budswell) added 2-3 weeks of control to Prowl/Surflan alone providing almost 2 months of control at Lamont’s and 2.5 months at Mason’s. GoalTender also has burndown activity to take care of winter annuals present.

There were 3 treatments at Mason’s that included Matrix (sulfonylurea – pre and post) which stops growth of root tips and shoot tips – death. But there were only 2 Matrix treatments in the Lamont planting in combination with Surflan to be able to observe any impact on tree growth as expected from label restrictions for use in 1 yr established trees. The 2 treatments with Surflan included at Lamont’s lasted 57-65 days, but all 3 treatments with Matrix at Mason’s lasted 3 months. The Matrix application alone was sufficient for control with potential for cost savings. Matrix also has post-emergence activity.

All treatments at Mason’s except for the Matrix and Alion treatments required 2 post-emergence treatments. The GoalTender combinations and Surflan plus Chateau treatments at Lamont Fruit Farm only required 1 post-emergence application. The growing season at Lamont’s was a month shorter to combat weeds.

Tree growth measurements in trunk cross sectional area in cm2 before growing season compared to the end of growing season are shown in Tables 1 and 2 as % change in TCA. The greatest statistical increase in TCA at Lamont’s was in the plots with Prowl/Surflan, Chateau, GoalTender, and Sinbar. The Surflan plus Matrix treatment was numerically better than the untreated check but not statistically separated, but when combined with GoalTender, was one of the better (although more expensive) treatments. Green Match and the untreated check had the least increase in TCA due to the weed competition.
Tree growth measurements in Mason’s Farm did not show as much separation with untreated check at 86% increase vs. 139-165% increase in Surflan/Prowl alone, Prowl + Chateau, Surflan + GoalTender, Matrix, diuron + simazine, Alion, GreenMatch, and Pindar + Prowl. All other treatments were not statistically different from the check or the best treatments. The reduced effect on tree growth in this plot was likely due to the established root system by the second year in the orchard, with roots developing below the seed germination and root zone, reducing the potential competition by the weeds.

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, and the some of the combinations with Chateau (Prowl or Surflan) and Goaltender (plus Prowl or Surflan) in the newly planted orchards required only a single follow-up post-emergence treatment. Other required 2 post-emergence applications. The shortest residual treatments were the Prowl or Surflan alone. The longer season in the Mason 1-year established orchard resulted in most herbicide treatments needing 2 Gramoxone applications compared to 1 Gramoxone application in most of Lamont treatments.

Green Match, the OMRI certified organic herbicide, provided the same weed control as the untreated check in newly planted orchard, and slightly better in the 1st 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. But there was a bigger impact on tree growth in the newly planted orchard than the 1st year established orchard.

• Table 1 and Table 2, % weed cover, and tree growth

Collaborators: