|
|
|
|
How to Manage PestsUC Pest Management Guidelines
DESCRIPTION OF THE PESTOmnivorous leafroller is primarily a pest of peaches in the San Joaquin Valley. It occurs in the Sacramento Valley but seldom causes damage. Omnivorous leafrollers overwinter as immature larvae in mummy fruit or on winter weeds and do not enter a true dormancy. Larvae are light colored with dark brown or black heads. When mature they are about 0.6 inch (1.5 cm) long and have two slightly raised, oblong whitish spots on the upper surface of each abdominal segment. Abdominal segments may have a greenish brown tinge. They pupate inside a webbed shelter. Adults of the overwintering generation emerge by March 1. They are small, dark brown moths, 0.5 to 0.375 inch (9–12 mm) long with a dark band on the wing and a long snout. Eggs are laid in overlapping rows that resemble fish scales. The first generation of eggs usually is laid on weed hosts, and adults from this generation emerge in May or June to lay eggs in orchards on leaves and fruit. Larvae that hatch from this generation of eggs can cause significant damage in stone fruits. Like fruittree leafroller and obliquebanded leafroller, they have the characteristic behavior of wriggling backward when disturbed and dropping from a silk thread attached to the leaf or fruit surface. DAMAGEOmnivorous leafroller larvae often web leaves into rolled protective shelters while feeding. They feed on leaves and on the surface of fruit, sometimes webbing one or more leaves to the fruit for protection. They chew shallow holes or grooves in the fruit surface, often near the stem end, and webbing is usually present on fruit. Primary damage results from fruit feeding. Young fruit may be destroyed, and scars on older fruit will cause them to be culled or downgraded at harvest. Feeding injury also may increase the incidence of brown rot and other fruit decays. MANAGEMENTOmnivorous leafrollers do not usually appear in peach trees until early summer. Regular monitoring each season is important so that prompt action can be taken if damaging populations develop. Throughout the season, watch for the presence of leafroller larvae while monitoring. Biological Control Cultural Control Organically Acceptable
Methods Monitoring and Treatment Decisions Degree-day
calculator Degree-day
table From the first biofix, accumulate degree-days (DD) to estimate when the onset of the second flight will occur. Use a lower threshold of 48°F and an upper threshold of 87°F. (For assistance in calculating degree-days, see "Degree-days ") It takes about 1168 DD for omnivorous leafroller to develop from egg to adult. As the start of the second flight nears, be sure to have fresh trap liners and lures in place. When the second flight biofix is determined by trap catches, begin accumulating degree-days. Research in the central San Joaquin Valley indicates that the optimum single treatment timing is between 700 and 900 DD after the start of the flight. Monitor the fruit closely for signs of damage. No treatment threshold values are available. Examine fruit on trees every other week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results for the harvest sample.
IMPORTANT LINKS
PUBLICATION![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg){kind=logo}
UC IPM Pest Management Guidelines: Peach PDF: You need a PDF reader, such as Acrobat Reader version 8 or later, to view or print this PDF. If no reader is installed on your computer, you can download a free copy of Adobe Acrobat Reader. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
![[Precautions]](/IMAGES/btn-precautions_bul.gif)