2001-2002 Snow Mold (Typhula ishikariensis and T. incarnata)

The corporation-sponsored snow mold fungicide field study was conducted during the fall and winter of 2001-2002. Treatments were applied preventively on the Treetops/Sylvan Resort in Gaylord, MI on the dates indicated in Table 1. Treatments were applied to four replicate 6’ x 9’ creeping bentgrass (Agrostis palustris)/annual bluegrass (Poa annua) fairway plots where the turf was maintained at approximately ½” height of cut. Liquid treatments were applied with a CO2 backpack sprayer at a pressure of 36 PSI and a volume of 100 GPA using a flat-fan, double-nozzle boom, unless otherwise indicated in Table 1. Granular products were pre-weighed and hand-applied.

Permanent snow covered the plots from late December through April 13. The study was rated on 16-April, 2002 immediately following snow-cover melt-off. The predominant snow mold species was Typhula ishikariensis with lesser amounts of Typhula incarnata. Microdochium patch (Microdochium nivale) was also observed and was the predominant snow mold on some plots as indicated in Table 1.

As can be seen in Table 1, disease pressure was only moderately severe at Tree Tops this year. Disease pressure was also somewhat uneven across the study, leading to variability in the data, except with the most efficacious treatments. As in recent years, tank mixes of standard fungicides of varying chemistries seemed to perform the best. Interestingly, 18 of the 19 best performing treatments all included chlorothalonil or PCNB.

Phytotoxicity and turf greening effects were observed in some plots, as indicated the data table.

Table 1. Michigan State University Snow Mold Data, 2001-2002

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Dollar Spot (Rutstroemia floccosum)

This study was set up in 4 replicates of a random block design with 2’ x 6’ plots. We used a CO2 backpack sprayer with a single nozzle boom at 34 PSI and 48 GPA. The host was Emerald creeping bentgrass mowed at 3/16”. Fertility was maintained at about 3/8#N/month/1000 ft². The 7-day treatments were applied 8/1, 8/8, 8/15, 8/21, 8/29, 9/6, 9/12 and 9/18 (except as noted in the data table). The 14-day treatments were applied 8/1, 8/15, 8/29, and 9/12 (except as noted in Table 2). The 21-day treatments were applied 8/1, 8/21, and 9/12. The 28-day treatments were applied 8/1 and 8/29. Data represent mean percent plot area infected (Table 2).

As the data in Table 2 indicate, dollar spot disease pressure was moderately severe in this study. The DMI fungicides (Banner Maxx, Propiconazole) alone, and in combinations, performed well throughout the rating period. Chipco 26GT and Iprodione Pro performed well on a 14-day schedule and the new strobilurin fungicides performed well also. After pretreatment disease was eradicated, chlorothalonil (Daconil, Echo, Concorde) also performed well by the end of the season. It should be noted that the dollar spot strains in this plot area are benzimidazole-resistant, explaining the failed efficacy of Cleary’s 3336F. No phytotoxicity was observed in this study this year although turf quality varied greatly as indicated in Table 3.

Table 2: Putting Green Dollar Spot 2002.

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^a Means followed by the same letter do not significantly differ (LSD, p=0.05). ^b Benzimidazole resistant strains. ^c These program treatments were initiated on 5/22/02, with applications of 16A and 17A. 16B and 17B through 16H and 17H were applied at 14 day intervals ending with the final applications of 16H and 17H on 9/12/02. ^d Ionized copper was initially applied on 8/16/02, and re-applied on 8/22/02, 8/29/02, 9/6/02, 9/12/02, and 9/18/02. ^e Applied combination on 8/1/02, 8/14/02, and 8/29/02 due to disease >5%. Only 710-140 applied on 9/12/02. ^f Fungicide only applied on 8/1/02, 8/14/02, and 9/12/02. 710-140 only applied on 8/29/02. ^g Applied on 8/1/02, 8/5/02, 8/8/02, 8/14/02, 8/29/02, and 9/12/02. ^h Applied in 3 gal/1000 ft² spray volume.

Applied in 2 gal/1000 ft² spray volume.

Table 3. Dollar spot quality ratings^a Rating scale: 10 = best, 0 = worst, and 7= acceptable

a

Ratings based on color, density, and uniformity.^b Mean of 4 replicate plots. ^c Treatment applied in 3 gal/1000 ft² spray volume.^d Treatment applied in 2 gal/1000 ft² spray volume.

Anthracnose (Colletotrichum graminicola)

The anthracnose study was set up on an annual bluegrass fairway at the Hancock Turfgrass Research Center in E. Lansing, MI. It was mowed at ½”. The design was a randomized complete block with 4 replicates of each treatment. Plots were 6’ x 6’. Treatments were applied using a CO2 backpack sprayer with a double 8002E flat fan TeeJet nozzle boom at 48 GPA and 34 PSI. Plots were fertilized at about 3/8#N/1000 ft²/month. A 2 oz/1000 ft² rate of Chipco 26GT was applied on 19 June, 1 July, 11 July, 25 July, 6 August, and 21 August for dollar spot control. All preventive treatments were applied beginning on 4 July (except for the Program treatment which was applied as per the Table 4) with subsequent applications of the 14-day treatments on 16 July, 23 July, 30 July, and 15 August. Re-applications of the 28-day treatments were made on 30 July. Curative treatments were applied beginning on 18 July with subsequent applications on 30 July and 15 Aug. Plots were rated for percent area with anthracnose. Data are shown in Table 4 and represent the mean percent plot area with anthracnose. Data were analyzed using ANOVA and means separated with LSD (p=0.05).

On the July 19 rating, disease pressure was light with the control exhibiting 8% disease, and no significant differences occurring between treatments. As can be seen by the August 20 means, disease pressure remained light. However by this time, several treatments provided significant anthracnose control compared to the untreated control including the preventive treatments such as Banner Maxx and Daconil Ultrex, alone and in combination, Cleary’s 3336, the Program treatment (see Table 4), and the curative treatments Spectro and Endorse (6 oz/1000 ft²). Surprisingly, Heritage did not provide disease control as expected. No phytotoxicity was observed in this study this year.

Table 4. Mean Anthracnose Ratings

^a Represents the mean of 4 replicate plots. ^b Means followed by the same letter do not significantly differ (LSD, p=0.05). ^c Represents percent recovery from the July 19 rating until the August 20 rating. ^d Program treatments were applied on the dates indicated with the last 6 combinations not being applied since the disease pressure waned. ^e Treatments applied curatively on 7/18, 7/30, and 8/15.

Melting Out (Dreschlera poae)

This study was set up on an irrigated Kenblue Kentucky bluegrass block at Hancock Turfgrass Research Center, E. Lansing, MI. The study consisted of 4 replicates of each treatment, set up in a randomized complete block design with plots measuring 6’ x 9’ with 1’ alleys. Plots were mowed at 2.5”. Treatments were applied preventively, beginning on May 15 using a CO2 backpack sprayer at 34 PSI with 8002E flat fan nozzles. Subsequent applications for the 14-day treatments were made on May 29 and June 11. The spray volume used was 2 gallons per 1000 ft². Fertilizer was applied as follows: May 15 (1/4#N), May 28 (1/4#N), and June 11 (1/4#N). Plots were rated on a 0-10 scale where 0= no disease and 10=100% leaves infected (see Table 5.) Data were analyzed with ANOVA and means separated with LSD (p=0.05). No phytotoxicity was observed in this study this season.

As the data in Table 5 indicate, Endorse gave statistically significant control of melting out through the June 21 rating. Disease pressure was relatively light this year as we experienced a cool, dry spring. This low disease pressure resulted in poor statistical separation between the untreated control and the Chipco 26GT. No significant quality differences or phytotoxicity was observed.

Table 5: Mean Melting Out Ratings

^a Means followed by the same letter do not significantly differ (LSD, p=0.05).

Brown Patch (Rhizoctonia solani)

Two preventive studies were set up this year, one on a ryegrass plot area and a second on a bentgrass green at the Hancock Turfgrass Research Center, E. Lansing, MI. Both studies were randomized complete block designs with 4 replicates of each treatment. Plots measured 2’ x 4.5’ with 1’ alleys. Treatments were applied using a CO2 backpack sprayer at 34 PSI and 48 GPA, unless otherwise noted in Table 8, using a single 8002E Tee Jet flat fan nozzle. Subdue Maxx was applied at 1 oz/1000 ft² on 7/3, 7/18, and 7/30 to prevent a Pythium blight outbreak. The study area was inoculated (6/24, 7/11, 7/30) with Rhizoctonia solani growing on a sand/cornmeal mixture using a drop spreader at approximately 2.5#/1000 sq ft. Plots were fertilized at a rate of 1.25# N/1000 ft²/month on the ryegrass area and a rate of 0.75# N/1000 ft²/month on the bentgrass study. Treatments were applied beginning on June 24 unless otherwise noted in Table 8. The seven day combination treatment (Magellan + Mancozeb) was reapplied on 7/1, 7/8, 7/16, 7/23, 7/30, 8/6, and 8/15, and the Spotrete from the alternating combination treatment on 7/8, 7/30, and 8/15. Subsequent applications of the 14-day treatments were made on 7/8, 7/23, and 8/6. The 21-day treatments were reapplied on 7/16 and 8/16, and the 28-day treatments on 7/23. Application of the curative treatment (Spotrete) was delayed in anticipation of disease development. The treatment was applied on 8/15 and, as a result, no data are available for this treatment in the preventive study. Plots were rated for percent area blighted by brown patch (see Table 8.) Data were analyzed using ANOVA and means separated with LSD (p=0.05).

A third study was set up curatively on an adjacent area on the bentgrass green after a relatively uniform brown patch outbreak occurred. The area was rated on August 2, just prior to treatment application, for percent plot area blighted by brown patch. All treatments were applied on August 2, except for the program treatment. The 7 and 14day treatments were reapplied on August 19. Plots were rated prior to the initial treatment and rating (see Table 9). Data were analyzed using ANOVA and means separated with LSD (p=0.05).

As the data in Table 8 indicate, disease pressure was very low in both preventive studies with the untreated control having a slightly higher mean in the ryegrass study than in the bentgrass study at 10.8%. As a result, separation of treatment means was not strong. Several treatments provided significant disease control at this low pressure level including Prostar, Insignia in combination, Heritage, Cleary’s 3336 alternated with Spotrete, Magellan and Mancozeb in combination, and Spectro.

Data in Table 9 represent the curative (third) study. Several treatments provided good curative control of brown patch including Heritage, Insignia in combination, Prostar, Iprodione Pro, Chipco 26GT, and Endorse.

Table 8. Preventative Brown Patch 2002.

^a Represents the mean of 4 replicate plots. ^b Means followed by the same letter do not differ significantly (LSD, p=0.05). ^c Treatment applied in a 3 gal/1000 ft² spray volume. ^d Treatment applied in a 2 gal/1000 ft² spray volume. ^e Treatment applied curatively beginning on August 15, however, disease pressure decreased, therefore no data are available for this treatment. ^f Treatment not applied due to lack of disease pressure.

Table 9. Curative Brown Patch 2002.

^a Pretreatment rating. ^b Represents the mean of 4 replicate plots.

^c Means followed by the same letter do not differ significantly (LSD, p=0.05). ^d Represents the percent recovery from August 2 until August 15. ^e Treatment applied in a 3 gal/1000 ft² spray volume. ^f Treatment applied in a 2 gal/1000 ft² spray volume. Note: Program Treatment omitted.

Red Thread (Laetisaria fuciformis)

This study was set up on a ryegrass fairway at the Hancock Turfgrass Research Center, E. Lansing, MI. The study consisted of 4 replicates of each treatment set up in a randomized complete block design with plots measuring 6’ x 6’. Treatments were applied curatively using a CO2 backpack sprayer at 48 GPA and 34 PSI with two 8002E flat fan nozzles. A pre-treatment rating was taken on 6/13 (Table 10), and then initial treatment applications were made. All treatments were applied on a 14 day schedule with subsequent applications made on 6/28, 7/11, 7/26, 8/8, 8/21, and 9/6. Fertilizer was applied as follows: 5/17 (1#N), 6/6 (1/8#N), 6/14 (1/8#N), 6/20 (1/8#N), 7/2 (1/8#N), 7/18 (1/8#N), 7/31 (1/8#N), and 8/6 (1/2#N). A second curative study was established on an adjacent colonial bentgrass/annual bluegrass fairway plot area. Plots measured 6’ x 9’ and were initially treated on June 14 with subsequent applications made as stated above. Plots were rated for percent area infected with red thread. Data were analyzed with ANOVA and means separated with LSD (5%).

Disease pressure was very low in this study this year with the control having a maximum mean of 5%. With such low pressure, treatment means did not separate from each other statistically, but all provided good control of red thread compared to the control. No phytotoxicity was observed.

^a Pretreatment rating. ^b Represents the mean of 4 replicate plots. ^c Means followed by the same letter do not differ significantly (LSD, p=0.05).

Summer Patch (Magnaporthe poae)

This study was established on an irrigated annual bluegrass fairway at the Dearborn Country Club in Dearborn, MI. The study consisted of 4 replicate 6’ x 9’ plots in a random block design. Treatments were applied preventively with a CO2 backpack sprayer at 34 PSI and 100 GPA (except as noted in Table 11). Treatments were initiated on 6/10/02 when we reached 75?F at a 2” soil depth. The 14 and 28-day treatments were re-applied as indicated in Table 11. Fertility was maintained at 1/2#N/1000 ft²/month. The study was background sprayed with 2 oz Echo (chlorothalonil) and 1 oz Subdue Maxx on 7/23 to control dollar spot and Pythium. Data represent percent plot area diseased on 7/23 and 8/20 when disease development peaked.

As the data in Table 11 indicate, summer patch disease pressure was moderately severe this year due to the warm, stressful summer we experienced. Under these stressful conditions, many treatments that controlled summer patch in the early rating (7/23), failed to control summer patch disease as the summer progressed and disease pressure increased (8/20 rating). Surprisingly, the strobilurin fungicides (Heritage, Insignia, Emerald) failed this year, except in combinations. The propiconazole fungicides, thiophanate methyl fungicides, TADS 12529, and Lynx + Compass are among the treatments that performed significantly better than the untreated control this year. No phytotoxicity was observed in this study.

^a Means followed by the same letter are not significantly different (LSD, p=0.05). ^b One or more replicate plots within treatment displayed superior turfgrass quality/color on 8/20/02. ^c Treatment applied in 3 gal/1000ft² spray volume.

Take-All Patch (Gaeumannomyces graminis) 2001-2003

This multi-year take-all patch disease study is being conducted on an irrigated and diseased creeping bentgrass fairway at the Golf Club of Michigan, Brighton, MI. The study is setup in four replications of a randomized complete block design utilizing 6’ X 9’ plots, each of which has displayed active take-all in recent years. Applications were made with a CO2 small plot sprayer with flat fan 8002E nozzles, operating at 36 PSI and approximately 100 GPA. Fertilizer treatments were pre-weighed and hand applied.

Because take-all patch is most severe under low fertility conditions, we applied only 1#N/1000 ft² of background fertilizer this season, except in the fertilizer treatments. This level of fertility was deemed adequate to promote fungicide efficacy while not discouraging disease symptom development. Fertilizer (18-3-12) was applied as follows: ¼#N/1000 ft² on 5/14/02 and 8/13/02; and 1/8#N/1000 ft² on 6/14/02, 7/12/02, 7/26/02, and 9/11/02. Chlorothalonil and metalaxyl fungicides were applied at low rates on 7/12/02 and 8/2/02 to control dollar spot and Pythium blight in the study.

As in 2001, take-all patch in this study developed in the spring once again. As the data indicates, however, disease pressure was modest and occurred somewhat unevenly in the study. This variability led to poor statistical separation between the treatment means of all the fertilized treatments. On the other hand, the benefit of fertility in take-all patch management is evident by comparing the unfertilized control with many of the fertilized treatments, most of which exhibited significantly less disease than the unfertilized control.

Golf Club of Michigan, Brighton, MI