Nine herbicide treatments were applied to non-overseeded bermudagrass (Arizona Common) on March 3, 1994 (for single applications) and on March 3 and April 29, 1994 (for split applications). The chemical products included treflan and balan (TEAM), prodiamine (BARRICADE) and pendimethalin (PROWL or PRE-EM) each at 3 different rates or as split application treatments. Mean crabgrass control ranged from 89-100% throughout the test period, ending April 26, 1994.

Pendimethalin as a split treatment (1.5+1.5 lb. ai/a) provided essentially 100% season long control, followed by pendimethalin at the one time application of 3.0 lb. ai/a. The prodiamine treatments ranged from 97-100% control. TEAM-on-fertilizer ranged from 93-100% control. For TEAM products it appeared that the split applications of 1.5+1.5 lb. ai/a and the one time application at 3.0 lbs. ai/a had better mean control than the single application of the 2.0 lb. ai/a rate. All herbicide/fertilizer products at rates tested here generally provided mean turfgrass color scores greater than the check (2 out of ratings).
 

Crabgrass (Digitaria spp) and southwest cupgrass represent two of the most prevalent annual grassy weeds in mowed desert turfs. A field test was conducted to investigate the efficiency of select pre-emergence herbicides for control of crabgrass on non-overseeded bermudagrass.
 

Nine chemical treatments and a control were included in a test at the Rincon Vista Track Field, University of Arizona. Plot size was 3' x 7' in an area with prior infestation of crabgrass. TEAM-on-fertilizer, prodiamine (BARRICADE) and pendimethalin (PROWL or PRE-EM) were applied at prescribed split or full application rates. Treatments were applied with a 30" wide Gandy Sprayer calibrated for each product/rate combination. Turf was a 25 year old stand of common bermudagrass (Cynodon dactylon) mowed weekly at 1.25 inches. Experimental design was a RCBD with four replications.

Plots were treated initially on March 3, 1994, with a second split application applied on April 29, 1994 (where applicable). The turf was evaluated for % control on six occasions (based on % of check plots), and for color or % bermuda cover on six dates. All plots received 3/8" water after application and 1.50 - 1.75 inches weekly, to avoid visual stress.
 

Weed Control:
On five out of six dates of evaluation, weed control due to treatments was not significant using the ANOVA technique. Weed control ranged from 89% to 100% throughout the entire evaluation period of June 14 to August 26, 1994. At the close of the experiment in 1994, the herbicide effect was significant as some treatments allowed crabgrass six months after application.

June 14, 1994:
Prodiamine at the 1.0 and 0.75 lb. ai/a rates provided 100% early season control, while the 0.5 lb. ai/a rate gave 98% control. Pendimethalin at the 3.0 and 1.5 + 1.5 ai/a rates had 98% control, while the single 1.5 lb. ai/a rate yielded 95% control. TEAM applications all provided 96-97% mean control. Once again, there were no significant differences due to treatments, with all treatments providing high levels or complete control (Table 1).

June 29, 1994:
Levels of control increased to 100% for all treatments, with the exception of pendimethalin at the 1.5 lb. ai/a rate (93% mean control). Apparently, small single tillered crabgrass plants noted previously were not able to withstand competition from encroaching bermuda.

July 22, 1994:
Pendimethalin at the 1.5 + 1.5 lb. ai/a treatment provided 100% control, while the single application at 3.0 lb. ai/a provided slightly less control (98%). The single rate at 1.5 lb. ai/a yielded 90% control. Prodiamine treatments provided 98% control. TEAM at the 1.5 + 1.5 lb. ai/a treatment provided 99% control, versus 98 and 90% control for the one time applications of 3.0 and 1.5 lb. ai/a treatments, respectively.

August 3, 1994:
TEAM at 1.5 + 1.5 lb. ai/a rate and the single 3.0 lb. ai/a treatment provided 100% control, along with pendimethalin (1.5 + 1.5 and 3.0 lb. ai/a treatments). The single application of other products at the lower rates (applied once only) yielded 94-99% mean control. Pendimethalin at the single application of 1.5 lb. ai/a had 94% control.

August 17, 1994:
All treatments had 100% control, with the exceptions of prodiamine at 0.5 lb. ai/a, pendimethalin at 1.5 lb. ai/a and TEAM at 2.0 lb. ai/a. Once again, there were no statistical differences between herbicide treatments.

August 29, 1994:
Late season crabgrass pressure was evident, as percent weed control ranged from 90-100%. The pendimethalin split applications 1.5 + 1.5 lb. ai/a and pendimethalin at 3.0 lb. ai/a provided 100% control. TEAM rates provided 98% mean control. The weakest treatment was pendimethalin at 1.5 lb. ai/a (90% control).

Turfgrass Response

March 29, 1994:
Mean color scores ranged from 5.3 to 7.0 among treatments. The check plots (no treatment) had the lowest color score of 5.3. Pendimethalin and prodiamine products had mean color scores of 6.25 -7.0, with the exception of pendimethalin at the 1.5 lb. ai/a rate. Since the second split application was not applied until April 29, 1994, differences between treatments with the same application rate ( on March 3), may be due to mowing patterns and traffic effects. There were no turf color differences due to these treatments on March 29.

April 19, 1994:
Significant color responses for the bermuda occurred by April 19, 1994. The check plots averaged 4.8, while TEAM at the 3.0 lb. rate had mean turf color scores of 7.8. This was followed by pendimethalin (3.0 lb. ai/a) and TEAM (2.0 lb. ai/a) which had mean color scores of 7.3 and 7.0, respectively.

June 14, 1994:
Mean color scores ranged from 7.8 to 9.0, as the bermudagrass peaked in performance at this time. TEAM at 3.0 lbs. ai/a and prodiamine at 1.0 lb. had the highest mean color score of 8.5 or greater.

June 29, 1994:
Mean color responses were significant due to product treatments, ranging from 3.8 (check - no treatment) to 5.5 for prodamine at 0.5 lb. ai/a. Team at 1.5 + 1.5 lb. ai/a produced mean turf color scores of 5.0.

July 22, 1994:
Mean color scores ranged from 6.75 to 7.5. There were only trace differences in color and the treatment effect was not significant at this time.

August 3, 1994:
Mean color scores ranged from 4.3 to 5.3, with no significant effect due to products applied. This was the last turf evaluation for the season. No other fertilizers were applied during the course of this study.

Table 1. Mean¹ percent crabgrass control of select pre-emergence herbicides. University of Arizona, 1994.

TEAM 1.5+1.5 96 100 99 100 100 98

TEAM 2.0 96 100 96 99 93 98

TEAM 3.0 97 100 98 100 100 98

Prodiamine 0.5 98 100 98 97 97 98

Prodiamine 0.75 100 100 98 99 100 100

Prodiamine 1.0 100 100 98 100 100 99

Pendimethalin 1.5 95 94 90 94 94 89

Pendimethalin 1.5+1.5 99 100 100 100 100 100

Pendimethalin 3.0 99 100 97 100 100 100

DATE MEAN⁵ 98 99 97 99 98 98

LSD VALUE⁶ -- -- -- -- -- 6.6

²Treatments applied March 3, 1994 (initial) and where applicable April 29, 1994 (split application = 1.5+1.5 lb.ai/a).

³Rates of active ingredient/acre of herbicide.

⁴Percent control = 1- (actual percent weeds in plot/actual percent weeds in checks) x 100.

⁵Mean of all treatments on each date.

⁶LSD Value = Least significance difference value. Difference between 2 treatment means must be greater than the LSD value for true differences to occur between treatments. "--" indicates no comparison applicable based ANOVA P value of 0.05 or greater.

Table 2. Mean¹ turfgrass color response of select pre-emergence herbicides. University of Arizona, 1994.

Treatment² Rate³ 29 March19 April14 June 29 June 22 July 03 August

TEAM 1.5+1.5 5.8 5.5 8.0 5.0 6.8 4.5

TEAM 2.0 5.8 7.0 8.0 4.5 7.3 5.0

TEAM 3.0 6.0 7.8 8.5 4.3 7.3 5.0

Prodiamine 0.5 6.3 5.5 8.0 5.5 7.5 5.3

Prodiamine 0.75 6.3 5.8 7.8 5.3 7.0 5.0

Prodiamine 1.0 6.8 6.8 9.0 4.3 7.0 4.3

Pendimethalin 1.5 5.8 6.0 8.0 5.0 7.0 4.8

Pendimethalin 1.5+1.5 7.0 6.5 8.3 4.5 7.3 5.0

Pendimethalin 3.0 7.0 7.3 8.0 5.3 7.3 4.3

Check (none) -- 5.3 4.8 7.8 3.8 7.0 4.3

DATE MEAN⁵ 6.2 6.3 8.1 4.7 7.1 4.7

LSD VALUE⁶ -- 1.2 -- 1.2 -- --

²Treatments applied March 3, 1994 (initial) and where applicable April 29, 1994 (split application = 1.5+1.5 lb.ai/a).

³Rates of active ingredient/acre of herbicide.

⁴Color scores 1-9, 1 = dead turf 9 = dark green color.

⁵Mean of all treatments on each date.

⁶LSD Value = Least significance difference value. Difference between 2 treatment means must be greater than the LSD value for true differences to occur between treatments. "--" indicates no comparison applicable based ANOVA P value of 0.05 or greater.

Appendix Table A. Fertilizer/herbicide product analysis¹. University of Arizona, 1994. Pre-emerge crabgrass study.

TEAM-ON- 1.5 130 1.15G 27-3-8 .80 .09 .24

TEAM-ON- 2.0 174 1.15G 27-3-8 1.08 .12 .32

TEAM-ON- 3.0 260 1.15G 27-3-8 1.60 .18 .48

PRODIAMINE 0.5 227 0.22G 19-4-6 1.0 .21 .47

PRODIAMINE 0.75 340 0.22G 19-4-6 1.5 .31 .47

PRODIAMINE 1.0 454 0.22G 19-4-6 2.0 .42 .62

PENDIMETHALIN 1.5 124 1.21G 28-3-4 .80 .08 .11

PENDIMETHALIN 1.5 248 1.21G 28-3-4 1.60 .17 .22

FN: TEAMCOOL.94 O/N/D 94 CLH