Arboriculture & Urban Forestry 33(3): May 2007 213 Table 1. Powdery mildew (Sphaerotheca pannosa) disease severity in roses (Rosa spp.) treated with disease control products under different environments. Treatmentz Equate UltraFine Ajax Surround Neem Gold M-Pede Armicarb Bayleton Triact 70 Compass/Sevin Water control LSD(0.05) Application rate (product/L of water) 18.3 mL/L (1.8%) 14.0 mL/L (1.4%) 18.3 mL (1.8%) 30 g/L (0.25 lb/gal) 10.0 mL/L (1.0%) 8.3 mL/L (0.83%) 6.6 g/L (0.05 lb/gal) 0.9 g/L (0.12 oz/gal) 10.0 mL/L (1.0%) 0.3 g/L (0.04 oz/gal) — Greenhouse 2002 1.50 cd 1.80 bcd 1.10 d 1.50 cd 2.00 bcd 1.80 bcd 1.30 cd 2.10 bcd 1.20 cd 2.80 a 3.30 a 0.67 Highest disease severity (0–5 scale)y Shadehousex 2003 2002 1.00 d 1.50 bcd 1.13 d 1.75 bc 1.25 cd 1.63 bcd 2.00 b 2.00 b 1.75 bc 1.05 cd 4.50 a 2.00 def 1.87 efg 2.00 def 1.75 gf 1.87 efg 1.00 hr 2.37 bcde 2.75 bc 1.37 gh 2.50 bcd 3.50 a 0.66 in three environments Field 2002 1.50 cd 1.8 bc 1.10 d 1.50 cd 2.20 ab 1.80 bc 1.30 cd 2.10 bc 1.20 cd 2.80 a 3.10 a 0.57 2003 2.12 c 2.37 bc 2.00 c 2.37 bc 2.37 bc 2.37 bc 2.00 c 2.25 bc 2.75 b 2.12 c 3.87 a 0.67 0.60 zFungicides Bayleton (triadimefon) and Compass (trifloxystrobin) were applied starting early May and the insecticide Sevin (carbaryl) was added in a tank mix starting in mid-June when Japanese beetles were detected in insect traps. yDisease severity readings: 11% to 10%, 211% to 25%, 326% to 50%, 451% to 75%, and 576% to 100% plant showing symptoms. Numbers followed by common letters in the same column are statistically similar at P0.05 according to analysis of variance (Proc GLM) and least significant differences (LSD) calculated by Statistical Analysis Systems (SAS Institute 1990). xShadehouse experiment was repeated in 2004 and similar results were obtained (data not shown). eventually covered the entire leaf surface. In 2002, disease pressure was moderate with only 50% of the nontreated fo- liage showing symptoms in the shadehouse, field, and green- house trials. However, in 2003, disease pressure was high in greenhouse trial and moderately high in the field trial as indi- cated by disease severity in the nontreated plants (Table 1). All biopesticides, including household soaps (Ajax and Equate), bicarbonate salt (Armicarb, Helena Chemicals Company, Col- lierville, TN), neem seed oil extract (Triact 70, ThermoTriol- ogy Corp., Columbia, MD and Neem Gold, Biocontrol Net- work, Brentwood, TN), and kaolin clay (Surround, Engelhard Corp., Iselin, NJ), were effective in reducing powdery mildew disease severity (Table 1). Initial symptoms of black spot were observed in late May in shadehouse and field trials, but the disease did not develop in the greenhouse. Black spot symptoms in roses were char- acterized by black necrotic lesions (2 to 12 mm [0.08 in to 0.48 in] in diameter) that were circular or irregular in shape with radiate, feathery margins and a chlorotic halo (Figure 1B). Black spot disease was associated with defoliation and by mid-June, the nontreated plants had greater than 80% to 90% defoliation. Disease severity was moderate in 2002 and high in 2003 (Table 2), and the nontreated plants had defo- liated approximately 50% to 75% in 2002 and greater than 80% to 90% in 2003. Some treatments were slightly more effective than others in reducing black spot disease severity in individual trials. However, there were no statistical differ- ences between biopesticide and conventional fungicide treat- Table 2. Black spot (Marssonina rosae, anamorph Diplocarpon rosae) disease severity in roses (Rosa spp.) treated with different products under field environments. Highest disease severity (0–5 scale)y Treatmentz Equate UltraFine Ajax Surround Neem Gold M-Pede Armicarb Bayleton Triact 70 Insecticide and fungicide Control LSD(0.05) Application rate (product/L of water) 2002 18.3 mL/L (1.8%) 14.0 mL/L (1.4%) 18.3 mL/L (1.8%) 2003 1.50 cd 1.00 e 1.80 bc 1.50 bcde 1.10 d 1.13 de 30 g/L (0.25 lb/gal) 1.50 cd 1.75 bcd 10.0 mL/L (1.0%) 8.3 mL/L (0.83%) 6.6 g/L (0.05 lb/gal) 1.30 cd 2.00 b 0.9 g/L (0.12 oz/gal) 2.10 bc 2.00 b 10.0 mL/L (1.0%) 0.3 g/L (0.04 oz/gal) 2.80 a — 3.10 a 0.63 4.50 a 0.65 zFungicides Bayleton (triadimefon) and Compass (trifloxystrobin) were ap- plied starting early May and the insecticide Sevin (carbaryl) was added in a tank mix starting in mid-June when Japanese beetles were detected in insect traps. yDisease severity readings: 11% to 10%, 211% to 25%, 326% to 50%, 4 51% to 75%, and 5 76% to 100% plant showing symptoms. Numbers followed by common letters in the same column are statistically similar at P0.05 according to analysis of variance (Proc GLM) and least significant differences (LSD) calculated by Statistical Analysis Systems (SAS Institute 1990). ©2007 International Society of Arboriculture 1.20 cd 1.75 bcd 1.05 de 2.20 ab 1.25 cde 1.80 bc 1.63 bcde
May 2007
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
