Bud swell in grapes: Grape flea beetle and climbing cutworms

Hello, everyone,
At yesterday's vineyard IPM workshop n Madison County, vines were at bud swell.  This is a key time for a couple of pests.

Grape flea beetle adults feed on primary buds at this time.  This is mainly a problem in parts of blocks near wooded edges - but in such rows I have seen 40% of the primary buds destroyed.  This is a metallic blue-green beetle that is almost 5 mm long. Adults overwinter in debris in and near the vineyard. They become active early in the spring and lay eggs in cracks in the bark, at bases of buds, between bud scales, and on leaves. Eggs are light yellow and are laid in masses; they hatch in a few days and larvae feed on grape leaves for 3-4 weeks. Larvae are brown with black spots, and reach a length of 10 mm. Larval feeding damage consists of characteristic chain-like feeding marks on leaves, although occasionally this injury may appear more extensive. However, the damage by adult grape flea beetles is more important. The beetles eat holes into the sides of buds and gouge out the contents as the buds swell. Such injury occurs most prominently on thick-leaved grapes which have large buds, such as the American cultivars `Concord' and `Niagara'. It should be noted that climbing cutworms can cause similar damage. However, damage by the latter pest complex is usually more ragged in appearance. Adults also feed on the unfolding leaves.  For more information, visit http://www.virginiafruit.ento.vt.edu/GFB.html.

Climbing cutworms also attack primary buds, but injury can be more generally distributed throughout the block. 
The biology of the various climbing cutworms varies considerably but the peak flight periods and generations for some of the common species are listed above. The most common species have one or two generations per year and overwinter as half-grown larvae on the soil in leaf litter and orchard debris. A few other species overwinter as eggs or even as adults. The species which overwinter as larvae begin to become active as the weather warms, generally in mid-April. This group of moths derives its name from the larval habit of climbing trees to feed on buds and young foliage during the night, and then crawling back down to the ground to seek shelter under leaf litter, killed grass, or debris on the vineyard floor during the day. The larvae often curl up tightly when disturbed. Hundreds of larvae may feed on a single tree. The larvae mature by May and enter the soil to construct pupal chambers. In two-generation species, second generation feeding is minor. 
Most injury from climbing cutworms occurs in the spring when they feed on primary buds or young shoots. In severe cases, all buds may be killed, so that growth is delayed considerably compared to uninjured cordons.  While growth will likely resume later from secondary or tertiary buds, yield from such shoots is reduced, and harvest maturity is erratic, especially when considering bunches produced on other, uninjured vines.  For more information, visit http://www.virginiafruit.ento.vt.edu/cutwormsgrape.html.

More later,
Doug

Vineyard Pest Management Workshop.

There will be a vineyard IPM workshop held on April 17 at Early Mountain Vineyard, 6109 Wolftown-Hood Rd, Madison, VA 22727.  Specialists will discuss weed science, plant pathology and entomology, including updates on invasive pests.

Agenda:

11:00 am Welcome and vineyard management reminders- Tremain Hatch

11:30 Weeds and vineyard floor management – Jeff Derr

12:30 Lunch bring a bagged lunch

1:00 Worker Protection standards update – Micah Raub VDACS

1:45 Insect management for the vineyard – Doug Pfeiffer

2:30 Pathogen management in the Vineyard – Mizuho Nita

3:15 Grape IPM tool and scheduling exercise –Mizuho Nita

4:00 clean up and adjourn

Pear psylla management

Hello, everyone,

At this week's orchard meeting in Albemarle County, there was quite a bit of discussion on pear psylla.  With recent increases in pear acreage in the state, there is more interest in pear psylla, a key pest of pear throughout North America (originally introduced from Europe, along with pear - there are no native American pear species).  I am inserting below the pear psylla material from the Virginia Fruit web site - watch for updates as we adjust our management recommendations.  A key point to note now is the appearance of the eggs. Eggs are laid in spring by the overwintered adults, especially in the crevices at the base of fruit spurs.  These are light in color at first, later turning a light orange color.

Pear Psylla, Cacopsylla pyricola (Foerster)

I. Introduction: Pear psylla (PP) is the most important insect pest of pear in all pear-growing regions (Asian pear species are less susceptible). It is responsible in large part (along with fire blight) for the decline of cultivation of pear in the eastern states. It is the only one of several European pear psyllids to have been introduced into North America. It was first introduced into Connecticut around 1832, and reached Virginia (Charlottesville) by 1894. II. Hosts: PP develops only on pear.


III. Description: Summer form: The length of adults to the tip of folded wings is about 8/100 - 11/100 inch (2.0-2.75 mm). The color is light orange to red brown, with darker markings (four stripes along the back). The legs and antennae are mostly light brown to orange. Wings are clear with a conspicuous black spot on the hind edge (at the midline when at rest). Winter form: The length of adults to the tip of folded wings is 13/100 - 16/100 inch (3.3-4 mm). The body color is now very dark red-brown to black (Plate 87). The wing veins are very dark and conspicuous, and the wing spot is now more pronounced. In both forms, the head is a little over half as long as wide. The antennae are 1 1/2 times as long as width of head.
Eggs are pale cream to yellow-orange. They are elliptical in shape, with a tiny peg inserted into plant tissue. Nymphs are pale yellow when young, but have brown sclerotized plates when older. They resemble flat aphids in shape.




IV. Biology: Adults overwinter in or near pear orchards. Few adults are mated before overwintering. In early spring adults return to the trees, mate and begin ovipositing in crevices on fruit spurs and on young leaves as they unfold. There are three generations during the spring and summer. In the fall, when daylength falls below 13.5 hours, an overwintering form is produced which is darker than the summer adult. There is some degree of reduced fecundity in crosses between these forms.
Females lay an average of more than 300 eggs during their life. Most oviposition by summer adults occurs near leaf midveins; egg survival is also highest near midveins. As nymphs develop, they become engulfed in a droplet of accumulating honeydew. Such droplets may contain the shed skins of the preceding instars.
Recent research at USDA indicates that a transgenic pear line (developed for resistance to fire blight) may be less suitable as a host for pear psylla.


V. Injury: Although it is classed here as an indirect pest because it feeds on leaves, the main source of economic injury is to the fruit. Honeydew supports growth of sooty mold and causes a black russet on fruit; necrotic areas on foliage may also develop. PP serves as the vector for the mycoplasma-like organism causing pear decline when European scions are grown on Asian rootstocks. The latter problem is avoided by choice of rootstock/scion combination. Sooty mold and leaf injury may reduce photosynthesis and return bloom.




VI. Monitoring: PP may be monitored in several ways. In the spring, examine growth scars on spurs and twigs for the appearance of the first eggs. This method is used to time the delayed dormant application. Adults may be monitored by a beating tray method or with yellow sticky traps. A beating tray size of 18x18 inches (45x45 cm) was used in Connecticut; the tray is held beneath a limb and the limb is jarred three times in succession, sampling four limbs on each of 10 trees per block. Adults are counted on the surface of the tray.
Action should be taken when the first eggs laid in the spring appear. Research in Washington State has found that a peak density of 0.3 nymphs/leaf causes detectable fruit injury on both `Anjou' and `Bartlett'. Populations causing 9 and 18 nymph-days per leaf caused injury on the two varieties, respectively, with no significant effect of period during the season. Averages of 1.0-1.2 adults per beating tray or 4.4-6.9 adults per sticky trap were recommended as action thresholds by Connecticut researchers.


VII. Control: Dormant oil may be applied when eggs begin to appear in spring (see photo above). Various insectides are registered for post bloom control. Horticultural spray oil may be applied.  This is more highly refined than dormant oil and should not be confused.  Also, a lower rate is used, 1 qt/100 gal, rather than the 2 gal / 100 gal recommended in dormant sprays.  Horticultural spray oil is recommended to be included with avermectin sprays.