Posts Tagged: insect damage
The Pretty, Persistent Peach Tree Pest
Late July, while foraging through peach tree branches to pick the ripe fruit, I paused to stretch my back and was inundated with sawdust tumbling off the leaves. The more I looked, the more I realized the woody grains were localized in one area. Figuring the wind carried the debris onto my backyard tree, I hosed it off and went on with the day. But after several occasions of being greeted with a layer of sawdust on the same leaves, I grew curious. During an inspection of the old tree, I discovered two bore holes that penetrated into the wood over three inches deep with the openings as round as my index finger.
What on earth is drilling such large holes in this tree? I wondered.
After research revealed the attacker was a peach tree borer, Synanthedon exitiosa, I kept watch for the adult insect and larvae whose photos are displayed online at http://ipm.ucdavis.edu/PMG/r602301211.html (click the first word of the third sentence: Adults.) Although I never saw the “Adult peach tree borer” featured in one of the photos (which I later learned is the smaller more slender male whose both wings are transparent), I did see the female in my tree.
And let me tell you, this gal was gorgeous. She measured about one and a half inches long and sported a dark almost black steel-blue body with dark black-like forewings and clear hind wings with black margins. A brilliant orange band encircled her abdomen. (See photo below and visit http://bugguide.net/node/view/216752/bgpage for a great closeup shot).
Needless to say, I stood beside my peach tree transfixed — debating whether to bolt for the kitchen bug killer or race to the far end of the house to get my camera. The spray can won, so I let that flying flirt flitting through the branches have it. Despite searching both tree and ground for her body to preserve for pictures, I never saw the pretty and persistent Synanthedon exitiosa again.
Unfortunately, I learned that I’ll have to wait until next spring to know for sure if she’s really gone and how many borers she left behind. Since females lay an average of 500-600 eggs, who knows how many larvae are tunneling their way deeper through the bark and into the sapwood of my tree? Next spring I could come face to face with more culprits after pupation takes place and the next generation of moths emerge. To prevent the possibility of another attack, I filled the bore holes with the bug killer and my husband sawed off the large tree limb that was penetrated. In the meantime, I’ll encourage the ants, spiders and lacewings and the birds that prey on the eggs and larvae.
Adult male peachtree borer (photo UC IPM online)
Peach tree borer larva (photo UC IPM online)
Female peach tree borer (photo from Univ. of Kentucky Ag. dept)
Bore hole on side of limb - photo by Launa Herrmann
Peaches by Launa Herrmann
Unusual Wood-Boring Worms
Stephen Vasquez, Walt Bentley and Matthew Fidelibus
Over the last four years some growers have noticed an unusual worm in their vineyards. The worms are difficult to see if you are passively walking the vineyard but if you peel the old loose bark away from the head, trunk or cordons until you reach the newest bark, you may find holes with large white larvae (Fig. 1). The insect is a moth and has been identified as a member of the Givira genera, which have been mostly associated with old (>35 years) Thompson Seedless vineyards but have been found in vineyards planted to other cultivars too. Many of the older raisin vineyards located in Fowler/Del Rey and to the east in Sanger/Parlier area have documented this wood boring worm. Whether or not they cause direct economic damage is uncertain; most of the worms we saw seemed to be boring into dead wood. However, some growers have said they have seen these worms feeding on living cambial tissue and on young emerging buds and green shoots. Their burrows also offer refuge to vine mealybug, which is undesirable to growers trying to mange this pest.
Often what first attracts a grower’s eye is the adult cast left behind after emergence. The casts stick half way out of a bored hole in old wood (Fig. 2); resembling planes that crash dove into the wood. Figure 3 shows the cast pulled from the hole.
Currently, little is know about the moth’s biology but there are plans to do some trapping in March. Using black light traps, UC researchers hope to catch adult moths that can then be used to identify the species and give researchers a better idea of what potential management methods could be used to reduce populations. Additionally, surveys will take place to try to identify egg masses associated with this genus.
Stephen Vasquez is the UC Cooperative Extension Viticulture Farm Advisor in Fresno County. Matthew Fidelibus and Walt Bentley are Viticulture Extension Specialist and UC IPM Entomology Advisor, respectively, located at the UC Kearney Agriculture Center.
Givira-larvae
Givira-Adults cast in trunk
Givira-cast
New Invasive Vineyard Pest Found in California
European grapevine moth (aka European grape berry moth; (Lobesia botrana) was recently found in Napa County, a first known find for California. The insect has the potential to cause great economic harm to California’s diverse grape industries. The moth was trapped in Napa County’s, famous Oakville grape growing region known for high valued wines. Common to Europe and the Mediterranean, European grapevine moth has been intercepted from across the US where international travelers, cargo or mail disembark from planes originating from overseas. Currently, the Napa County Agriculture Commissioner is working with the CDFA and USDA to survey the area where the moth was first located in an attempt to detect additional European grapevine moths.
European grapevine moth identification
European grapevine moth can be confused with American grape berry moth (Endopiza viteana) native to the eastern United States or European grape berry moth (Eupoecilia ambiguella). Wings of the invasive European grapevine moth, L. botrana, have a mosaic shaped pattern with black-brown, cream, and gray-blue ornamentation (Fig. 1). Larvae tend to develop a purple cast after feeding and will often be found inside the berry. Samples should be taken to a trained university or state entomologist for proper identification and documentation. It is important to note that samples should be enclosed in a sealed container, jar, or vial if found prior to moving the insect (all stages) from an infested site.
Damage
Damage can be seen to both grape flowers and developing fruit. Larvae feed on flowers prior to bloom and continue through bloom. As bloom peaks, larvae protect themselves by producing webbing around the damaged flowers and feeding on neighboring flowers and parts. Second and third generation larvae feed on berries hollowing and contaminating them with excrements (Fig. 2). Cultivars that naturally have tight clusters—like Chardonnay, Pinot noir and Zinfandel—will suffer the most damage. Much like infestations from other worm pests, feeding damage will lead to infections by bunch rot fungi. Raisin and table grape cultivars will also experience damage, especially when bloom is prolonged due to weather, making flowers less responsive to applications of gibberellic acid used for bloom thinning. Table grape cultivars with tight clusters have the least tolerance for the moth due to fruit feeding damage and contamination with webbing, excrements and rot. All life stages can be found in vineyards infested with European grapevine moth but larvae from the second and third generations have been found to be the most damaging when fruit is maturing.
Host range
The host range for European grapevine moth is diverse. In addition to Vitis vinifera (cultivated grape), they also feed on other important agricultural crops like apple, cherry, nectarine, persimmon, plum, pomegranate and olive. It has been documented that privet and some grape cultivars are preferred for oviposition. Plants should be inspected for eggs, larvae and pupae. Larvae can be found in flower or fruit clusters along with webbing and in berries or other fruits. Pupae are frequently found inside a silken cocoon in rolled leaves, inside clusters, and under the bark of any of the previously mentioned host. At this time there are no regulations in place regarding the movement of fruit or other plant material from Napa County but growers and industry representatives should be vigilant. Trapping beginning at budbreak, using a tested pheromone is the best approach to monitoring vineyards for activity. Pheromones attract males to traps and allow one to estimate a population of European grapevine moth. With cooler fall temperatures, adult moths will be absent and only the diapausing pupal stage inside a silken cocoon can be found protected by grapevine bark. Growers should consult with their County Agriculture Commissioner or University of California personnel to determine the best approach to monitoring and properly identifying European grapevine moth.
Stephen Vasquez the UC Cooperative Extension viticulture farm advisor in Fresno County. Walt Bentley and Lucia Varela are UC IPM advisors in Fresno and Sonoma Counties, respectively.
Lbotrana-moth
Lbotrana-MC