Disease Resistance and Adaptability of Stellar and Flowering Dogwood Cultivars at Two Alabama Sites

Stellar® dogwood (Cornus florida × kousa) cultivars Aurora®, Constellation®, Celestial™, Ruth Ellen®, and Stellar Pink® were compared with selected flowering dogwood (Cornus florida) cultivars Cherokee Brave®, ‘Cherokee Princess’, ‘Cloud 9’, and ‘Rubra’ in a simulated landscape planting at sites in southwest (USDA Hardiness Zone 8a) and northeast Alabama (USDA Hardiness Zone 7a) for their reaction to the diseases spot anthracnose, powdery mildew, and Cercospora leaf spot. Tree longevity as influenced by the occurrence of the dogwood borer (Synanthedon scitula) and an ambrosia beetle (Xylosandrus sp.) was also assessed at both sites. All Stellar® dogwood cultivars generally proved resistant to the bract and leaf spot phases of spot anthracnose as well as powdery mildew and Cercospora leaf spot. While Cherokee Brave® was the only flowering dogwood with partial resistance to powdery mildew at both sites; this and the other flowering dogwood cultivars were equally susceptible to spot anthracnose and Cercospora leaf spot. Insect damage levels were higher at the southwest site than the northeast Alabama site. Within 3 years of establishment at the southwest Alabama site, incidence of tunneling damage attributed to dogwood borer and an ambrosia beetle was higher on the Stellar® dogwood than flowering dogwood cultivars, which also had higher values for tree longevity. In contrast, tree longevity was equally high and insect damage equally low at the northeast Alabama site for both the Stellar® and flowering dogwood cultivars. Superb resistance to the diseases spot anthracnose, powdery mildew, and Cercospora leaf spot translated into superior aesthetics and fall color for the Stellar® compared with the flowering dogwood cultivars at the northeast Alabama site. Hardiness of Stellar® dogwood cultivars in Alabama and possibly other southern states below USDA Hardiness Zone 7a is questionable due to tree vulnerability to the dogwood borer and ambrosia beetle.

A note on the activity and species composition of sesiids [Lepidoptera: Sesiidae] as measured by pheromone traps and trunk sampling in apple orchards of southwestern Quebec

Adult males and larvae of sesiids were monitored in ten (1989–1991), five (2000) and two (2004) Quebec apple orchards. Multi Pher III traps baited with 99.1% Z, Z-3, 13-octadecadienyl acetate and 0.9% Z, E plus E, Z-3, 13-octadecadienyl acetate were used for adults, and trunk sampling was used for larvae. Synanthedon scitula, S. pyri, Podosesia syringae, S. acerrubri, S. fulvipes, S. exitiosa, S. acerni and Sesia tibialis males were captured between 1989 and 1991. Only 5 of the 347 adults of the S. scitula/pyri complex captured in 2000 belonged to S. pyri.

Dogwood Borer, Synanthedon scitula (Harris) (Insecta: Lepidoptera: Sesiidae)

EENY-374, a 4-page illustrated fact sheet by Jamba Gyeltshen and Amanda Hodges, describes this destructive pest of flowering dogwood and other cultivated trees. Part of the Featured Creatures series, this publication covers the distribution, description, biology, host plants, damage, management, and selected references. Part of the Featured Creatures Collection. Published by the UF Department of Entomology and Nematology, May 2006. EENY-374/IN671: Dogwood Borer, Synanthedon scitula(Harris) (Insecta: Lepidoptera: Sesiidae) (ufl.edu)

Dogwood Borer (Lepidoptera: Sesiidae) Flight Activity and an Attempt to Control Damage in ‘Gala’ Apples Using Mating Disruption

‘Gala’ apple trees had a high incidence of burr knots (adventitious root primordia) produced on the trunk. Dogwood borer, Synanthedon scitula (Harris), infested many of these growths. Mating disruption using a sex attractant for dogwood borer, (Z,Z)-3,13-ODDA, did not control dogwood borer injury. In addition to other variables inherent to mating disruption (dispenser release and application rate, pest density, environmental factors), one potential reason for the failure was an inadequate conception of the dogwood borer sex pheromone composition. Therefore, the composition of dogwood borer pheromone should be reexamined. Traps baited with lilac borer, Podosesia syringae (Harris), lures were more sensitive for capturing dogwood borer males than traps baited with lures for dogwood borer. This is difficult to explain because the lures purportedly are identical. This difference in trap response further supports the need for reexamination of the pheromone blend compositions for each species. A complex of seven sesiids was attracted to both dogwood borer and lilac borer traps; captures of all were almost entirely eliminated by permeation with (Z,Z)-3,13-ODDA. There was a bimodal pattern of adult activity, with an early peak trap capture in May–June, and a later peak in July–August. The hypothesis of apple producing a later period of dogwood borer emergence than from dogwood was supported. This will complicate control in ‘Gala’ using current borer insecticides (e.g., chlorpyrifos, endosulfan) because of the proximity of harvest in this early-maturing variety with the ovipositional period of dogwood borer.

Infestation Levels of Dogwood Borer (Lepidoptera: Sesiidae) Larvae on Dogwood Trees in Selected Habitats in Tennessee

Infestation levels of dogwood borer [Synanthedon scitula (Harris)] on flowering dogwood (Cornus florida L.) in commercial nursery, urban, and forest habitats in eastern and middle Tennessee were measured during 1987 and 1988. The highest average infestation level (ca. 60%) was found in the urban habitat, where mechanical injury, e.g., damage caused by lawn mowers or string trimmers, may have provided oviposition or larval entry sites. Dogwood borer larvae were found in all nursery blocks examined, with ca. 7% of the trees infested/block. Infested trees are not marketable; thus, economic losses averaged ca. $l,800/block (x̄ = 1,770 trees/block) of dogwoods. Infestation levels were lowest (ca. 1%) in the forest habitat, where dogwoods grow as a natural component of the forest understory.

OBSERVATIONS, MONITORING, AND CONTROL OF CLEARWING BORERS (LEPIDOPTERA: SESIIDAE) ON APPLE IN CENTRAL ONTARIO

Observations on Malus domestica (Borkh) in central Ontario between 1981 and 1984 revealed that dogwood borer (Synanthedon scitula Harris) larval feeding was primarily associated with burr knots on the above-ground portion of apple rootstocks. Trunk injuries also served as sites of entry. Monitoring with pheromones indicated moth emergence occurred from late June until early August with peak activity occurring near the middle of July. Control of the dogwood borer on apple was obtained with 2 trunk drench sprays of dimethoate, fenvalerate, permethrin plus oil, endosulfan, parathion, chlorpyrifos, or lindane when applied during the period of adult flight activity.