July 23rd, 2001 Volume 10 No.19 Update on Pest Management and Crop Development
(Art Agnelloama4@nysaes.cornell.edu , Entomology, Geneva)
There are few real disasters being reported in the insect world just now, but some attention might be paid to a little bit of everything during this dog-day stretch, just to keep on top of the situation.
Oriental Fruit Moth & Co.
The second flight of this peach (and apple) pest started at the end of June, and we are now somewhat past the 6-day post-peak flight date to begin the second round of sprays. We recommend Asana in two applications, spaced 14 days apart. If you haven't begun treating for this generation of OFM, this week is still not too late to start.
There is a picture available here: http://www.nysipm.cornell.edu/factsheets/treefruit/pests/ofm/ofm_fig4.html]
Shoot-flagging injury from the first brood larvae is evident in Niagara Co. orchards by now, but those orchards relying on pheromone mating disruption seem to be holding their own. A little attention to orchard weed management now can help minimize later season catfacing injury.
This perennial pest overwinters as a partially grown grub in the soil below the frost line. In the spring the grub resumes feeding, primarily on the roots of grasses, and then pupates near the soil surface. Adults begin to emerge during the first week of July in upstate N.Y., and if you have looked at any roses lately, you know that they are right on schedule this year. The adults fly to any of 300 species of trees and shrubs to feed; upon emergence, they usually feed on the foliage and flowers of low-growing plants such as roses, grapes, and shrubs, and later on tree foliage. On tree leaves, beetles devour the tissue between the veins, leaving a lacelike skeleton. Severely injured leaves turn brown and often drop. Adults are most active during the warmest parts of the day and prefer to feed on plants that are fully exposed to the sun.
Although damage to peaches is most commonly noted in our area, the fruits of apple, cherry, peach and plum trees may also be attacked. Fruits that mature before the beetles are abundant, such as cherries, may escape injury. Ripening or diseased fruit is particularly attractive to the beetles. Pheromone traps are available and can be hung in the orchard in early July to detect the beetles' presence; these products are generally not effective at trapping out the beetles. Fruit and foliage may be protected from damage by spraying an insecticide such as Sevin (or Provado, if you're applying it to control aphids in peaches) when the first beetles appear.
(Information adapted from: Johnson, W.T. & H.H. Lyon. 1988. Insects that feed on trees and shrubs. Cornell Univ. Press.; and Howitt, A.H. 1993. Common tree fruit pests. Mich. State. Univ. Ext. NCR 63.)
Some remarks from last year by Dick Straub and Peter Jentsch on this perennial pest bear repeating about now, as we've been noting an increased number of reports of damage:
Non bearing trees: Because rapid shoot extension is critical, leafhoppers, and PLH in particular, should be controlled. This is not always easy to accomplish, given that PLH are terminal feeders and elongating shoots rapidly produce new leaves that are not protected by previous insecticide sprays. Even quasi-systemic materials such as Provado do not provide residual protection. Control, therefore, requires frequent applications to protect new foliage. If frequent applications (10-14-day schedule) are elected, it makes good economic sense to choose from any of the recommended contact insecticides for this purpose. Data from a recent trial, however, suggests that Provado at the reduced rate of 0.5 oz/100 reduces hopper populations and protects new foliage reasonably well when applied on a 14-day schedule. Given that the recommended rate for leafhoppers is 1-2 oz/100, the reduced rate renders Provado more economically attractive.
Bearing trees: In our opinion, PLH damage, although it may look bad, does not seriously affect either tree-growth or fruit-growth parameters. Shoot extension is not so important in bearing trees, and in fact, reduction of elongation or vigor may be desirable. A caveat to this philosophy, however, is the potential role of PLH as vectors of fire blight. Although this disease has not been prevalent this season, highly susceptible cultivars such as 'Gala' and 'Ginger Gold' etc., should be protected as much as possible from PLH feeding. This may be accomplished by frequent sprays as described above.
European Red Mite
ERM has started to build to problem levels in a number of regions of the state. We would recommend a check of highly susceptible varieties such as Red Delicious, Northern Spy, Jonagold, etc. at this time, using the July presence-absence chart with a 5.0 motiles/leaf threshold. Also, as usual, an eye should be kept on two-spotted spider mites (TSM), as this is the time (and type) of year when they can easily explode and begin bronzing leaves. It is apparent that some miticides having good efficacy against ERM are not necessarily effective against TSM. The question of how to rescue blocks from TSM was answered recently by Dick Straub's data from two trials at the Hudson Valley Lab. Under high TSM infestations (13-18 motiles/leaf by 3 Aug.), they evaluated single sprays of most currently available miticides. AgriMek (5 oz/100) + oil produced an 88.4% reduction of motiles; this material, however, would be ill-used as a rescue treatment, for a number of reasons. They were encouraged to find that Vendex 50W (8 oz/100) was highly effective, providing a 98% reduction of motiles at 21 days post-application in 1999, and 83% reduction 15 days post-application in 2000. Kelthane 50W (24 oz/100), applied against moderate TSM populations in 2000, provided fair (42% reduction) control of this species, but was relatively weak against ERM. Irregular results against TSM were provided by Pyramite (39% reduction in 1999, 84% reduction in 2000). Vydate (16 oz/100) provided surprising efficacy (83% reduction in 1999). This information should help in those orchard situations requiring treatment for 2nd generation leafminer.