Observations on the Biology and Control of the Hawthorn (Two-Circuli) Mealybug, Phenacoccus dearnessi (King)

Whitney Cranshaw; Zana Jevremovic; D. Casey Sclar; Loretta Mannix

doi:10.48044/jauf.2000.027

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Table 1.

Observations on the relative severity of hawthorn mealybug (Pseudococcus deamessi) infestations on various Crataegus cultivars. Plant Environmental Research Center (PERC), Colorado State University, 1994, 1995, and 1997.

Botanic name	Common name	Infestation level^z
Botanic name	Common name	1994	1995	1997
Crataegus arnoldiana	Arnold hawthorn	3.0	2.7	2.7
Crataegus crus-galli inermis	Thornless cockspur hawthorn	3.0	3.0	3.0
Crataegus douglasii	Black hawthorn	3.0	1.5	2.0
Crataegus laevigata ‘Toba’	‘Toba’ English hawthorn	3.0	3.5	3.5
Crataegus laevigata ‘Paul’s Scarlet’	‘Paul’s Scarlet’ English hawthorn	3.0	3.0	3.0
Crataegus laevigata ‘Crimson Cloud’	‘Crimson Cloud’ English hawthorn	3.0	2.5	2.5
Crataegus monogyna stricta	‘Upright Singleseed’ hawthorn	2.0	2.3	2.5
Crataegus pedicellata		2.0	3.0	2.0
Crataegus spp.		2.0	2.0	2.0
Crataegus rivularis		2.0	2.0	2.0
Crataegus × mordenensis ‘Snowbird’	‘Snowbird’ hawthorn	1.5	2.0	1.5
Crataegus succulenta macracantha	Macracantha hawthorn	1.0	2.0	1.0
Crataegus ambigua	Russian hawthorn	1.0	2.0	1.0
Crataegus phaenopyrum ‘Cordata’	‘Cordata’ Washington hawthorn	0.0	0.0	0.0

↵z Average infestation. Evaluations were typically made on 2trees per cultivar. Scale: 0 = no mealybugs present, 1 = 1-10 mealybugs per branch present, 2 = 11-50 mealybugs per branch present, 3 = 51-200 mealybugs per branch present, 4 = 200+ mealybugs per branch present.

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Table 2.

Hawthorn mealybug control trial, 1999.

Treatment^z and rate	Mealybugs/terminal^y
Avid 0.15EC 4.0 oz + SunSpray ultra-fine spray oil 2 qt/100 gal	0.25 c
SunSpray ultra-fine spray oil 2 gal/100 gal	1.33 c
293,343 25G 4.0 oz/100 gal	1.75 c
Astro 6.0 fl oz	3.00 c
293,343 25G 2.0 oz/100 gal	3.25 bc
293,343 25G 6.0 oz/100 gal	3.25 bc
Orthene TTO 0.5 lb/100 gal	12.00 b
Fulfill 5OWG 2.5 oz/100 gal	12.00 b
Untreated check	30.00 a

↵z Treatments applied 21 May, 1999. Evaluations were made 15 July by counting all mealybugs on the terminal 12 inches of four branches per treatment.
↵y Numbers not followed by the same letter are significantly different (P = 0.05) by SNK.

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Table 3.

Hawthorn mealvbug control trial. 1998.

Treatment and rate	Treatment date	Mealybugs/ terminal^z
Untreated check		58.75 a
Relay 50WG 5.0 oz/100 gal	15 May	18.50 be
Relay 50WG 2.5 oz/100 gal	15 May	14.75 ab
Relay 50WG 2.5 oz/100 gal + SunSpray 2 gal/100	15 May	18.75 ab
Merit 75W 0.52 oz/100 gal	15 May	5.75 cd
Merit 75W 0.52 oz/100 gal	27 May	21.50 ab
Astro 8 fl oz/100 gal	15 May	1.00 d

↵z Original data; data log transformed for analysis. Numbers not followed by the same letter are significantly different (P = 0.05) by LSD. Evaluations were made 10 June by counting all mealybugs on the terminal 30 cm (12 in.) of 4 branches per treatment.

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Table 4.
Effect of treatment timing on hawthorn mealybug control, 1999.
Treatment and rate Treatment date Mealybugs/terminal^z
Astro 6.0 fl oz/100 gal 15 May 1.2 c
Astro 6.0 fl oz/100 gal 22 May 2.4 c
Astro 6.0 fl oz/100 gal 1 June 12.6 b
Untreated check 46.4 a
↵z Original data; data log transformed for analysis. Numbers not followed by the same letter are significantly different (P = 0.05) by LSD. Evaluations were made 10 June by counting all mealybugs on the terminal 30 cm (12 in.) of 5 branches per treatment.