WSU Tree Fruit Research & Extension Center

Areawide II Project

Friday, March 22, 2019

Frequently Asked Questions

  1. Is Intrepid best timed for the eggs or larvae of codling moth?
  2. A bioassay showed that residues of Intrepid caused high mortality of developing codling moth eggs. In 2001 a single test indicated that oviposition timing provided better suppression of fruit injury than the more traditional egg hatch timing. Therefore, Intrepid has the unique ability to kill codling moth larvae as well as eggs as they develop. While we never rely upon a single test it does appear that Intrepid provide slightly better suppression of codling moth used as an ovicide. Either approach requires 2 or 3 cover sprays to achieve adequate control and Intrepid should always be used as part of a mating disruption program. (BRUNNER)

  3. What rate of Intrepid is best for codling moth control? For leafrollers? For lacanobia?
  4. To date all our experience with Intrepid is at the full field rate, 16 fluid ounces per acre. While it is likely that lower rates will work, especially against lacanobia and leafrollers, we do not recommend using lower rates until we have data to substantiate efficacy. Assessing the efficacy of lower Intrepid rates against these pests is an objective of research in 2002. (BRUNNER)

  5. Why are we increasingly seeing a late peak flight for the first codling moth generation?
  6. While we are not certain why this occurs it seems to be reported by more and more people in the fruit industry. In California there is a phenomenon known as the "B" peak. This is a second major peak of codling moth adult activity within the first generation. It is not clear that what is being observed in Washington is the same as the "B" peak in CA. The late peak of codling moth activity in the first generation could be related to a selection of codling moth over time to escape insecticide applications. That is, those moths emerging later from overwintering sites could avoid insecticide residues and over time more and more of these late emerging moths would comprise a larger and larger portion of the population, thus a form of behavioral resistance. This represents only a hypothesis that research will need to address.

    Moths detected in pheromone traps out of the normal pattern of emergence should be considered real and appropriate responses made if the numbers exceed treatment thresholds. Any abnormal pattern of moth activity points to the importance of monitoring. (BRUNNER)

  7. Do Washington orchards have much bio control of leafrollers? How significant can leafroller bio control be with the use of selective insecticides?
  8. There is little biological control of leafroller in most Washington orchards. This is primarily due to the continued use of organophosphate insecticides for codling moth control and use of carbaryl (Sevin) for thinning. These broad-spectrum insecticides suppress parasites and many predatory insects that could effect leafroller populations.

    The use of selective insecticides certainly opens a window of opportunity to enhance leafroller biological control in orchards. Insecticides like Intrepid, Bt products, and Esteem do not appear to negatively impact most natural enemies of leafrollers. If sufficient leafroller populations were allowed to exist in orchard to increase natural enemy densities it is possible that leafroller biological control could play a vital role in tree fruit pest management. (BRUNNER)

  9. The use of Assail has been shown to increase spider mite populations; how can this material be used to minimize this risk?
  10. Assail was registered in March of 2002 for use against codling moth and other pests of apple and pear. When Assail was used in a season long (4-spray) program time to control codling moth, spider mite densities were higher and predatory mite densities lower than organophosphate treatments or untreated controls. The best way to avoid spider mite problems is to limit the number of Assail applications. A good strategy would be to use Assail as a second cover, allowing workers to take advantage of the products short re-entry interval to continue activities such as fruit thinning. (BRUNNER)

  11. Is Lorsban needed in the delayed dormant spray on apples? What happens when this material is left out?
  12. Lorsban's primary impact as a component of delayed dormant sprays is against leafrollers. Lorsban provides some additional suppression of San Jose scale, though the oil, assuming it is included, is probably more important for this pest. Lorsban residues also suppress Campylomma densities around bloom time. While Lorsban cannot be relied upon to control Campylomma its use in the delayed dormant does influence the population of this pest. It is also possible, though not proven, that Lorsban use in the delayed dormant has a negative impact on some natural enemies in orchards.

    If Lorsban is left out of the delayed dormant sprays then other components of the pest control program become more important. The oil is relied upon for scale control and suppression of overwintering European red mite eggs as well as some suppression of aphid eggs. Oil does not affect leafrollers. We now have effective insecticides that allow us to control leafrollers at petal fall and these would be used instead of Lorsban. Campylomma densities could increase over time making monitoring and controls for this pest more important. There are insecticides that if properly timed provide good control of Campylomma. We do not know all of the things that might happen when we remove Lorsban from the delayed dormant period, which is why the Areawide II program is investigating this very question. (BRUNNER)

  13. What are the best timings to control codling moth and leafrollers with Intrepid? with Esteem?
  14. Intrepid applied at petal fall will control leafroller larvae and also provide suppression of codling moth by killing eggs. An additional application about 14 days later would be necessary for codling moth and high densities of leafrollers. It is possible that if a very high density of codling moth was present a third application 14 days following the second would be required. Intrepid should always be used in conjunction with codling moth mating disruption.

    Intrepid can also be used at the more traditional egg hatch timing, 250 degree days after biofix, for codling moth. Again 2 to3 applications at 114-day intervals will provide the best control. The last application would also provide some control of leafroller larvae of the summer generation. Summer leafroller control with Intrepid would be best when timed at the beginning of the egg hatch period, usually in early July.

    Esteem can be used like Intrepid at petal fall to control leafrollers and suppress codling moth. Esteem acts as an ovicide against codling moth. An application at petal fall and repeated in 14 to 21 days will provide suppression of codling moth but should be part of a mating disruption program. Leafroller larvae are killed by Esteem when they try to molt into a pupa. Leafroller larvae do not appear sick so it is difficult to evaluate the impact of Esteem until the summer when leafroller larvae just do not re-appear in the orchard.

    Esteem can only be applied two times per season and because of its long pre-harvest interval its use should be restricted to the period following bloom. (BRUNNER)

  15. Should oil or spreaders be used with the chloronicotinyls? with IGRs?
  16. This is a general question that is very difficult to answer completely or with certainty. In general the reason for using an oil or spread with a chloronicotinyl is to improve coverage and penetration in to the foliage. These products tend to have a short residual life on the surface of the plant but there is movement of the product into the plant where it remains active against sucking or chewing insects for a longer period of time.

    With IGRs the key is coverage since they usually need to be consumed to be effective or, in the case of their ovicidal activity, the egg must come into contact with the IGR residue. Therefore, any surfactant that would improve coverage should improve the efficacy of these products. (BRUNNER)

  17. Can sprayable pheromone be used to supplement CMMD, and if so, how should this be done?

    Yes, if a low rate of dispensers is used, you could put on sprayable during peak periods. It could also be used to treat borders or areas where the coverage is poor (upwind or tops of rises, etc.0. (V.JONES)

  18. Can "attract and kill" be used to supplement codling moth mating disruption?

    Only in a limited way - around the borders or possibly around bin piles. (V.JONES)

  19. Is the "attract and kill" approach suitable for codling moth control in a backyard situation?

    In theory it should, but there is some indication it will not. (V.JONES)

  20. Is CMMD cost-effective in small orchards (<5 ac) surrounded by backyards with infested apple trees?

    Probably not - there is too much immigration into the orchard. The shape of the orchard may also influence this - long and skinny would be the worst case. (V.JONES)

  21. The orchard borders are often where greater codling moth damage is found; what are the options for getting better control of the borders in a mating disruption block?

    Increase the rate of dispensers along the border, spot treat with insecticide around the border (4-5 rows inward), see if your neighbors will allow you to place dispensers in the first few rows of their orchard, place dispensers in wind break trees. (V.JONES)

  22. In what situations is the attract and kill approach (e.g. Last Call) best suited?

    Its probably best in smaller orchards, or as a supplement in organic situations where MD is not used, and it may have a fit in Leafroller management. (V.JONES)

  23. If even a relatively small amount (15-25% mortality) of biological control of codling moth can make a difference with mating disruption, what critters are attacking codling moth?

    A wide range of predators, depending on the crop, ground cover, and spray practices. Likely candidates include: ants, spiders, predaceous bugs, wasps (e.g. yellow jackets). (V.JONES)

  24. How do you recommend that the DA lure be used in 2002?

    Use it in conjunction with normal pheromone traps. Do not use it in pears or use it alone until more research is available to make sure the cultivar effects are not critical. (V.JONES)

  25. What is the best timing for sprayable codling moth pheromone?

    The initial application should be put on before moths are flying and be reapplied about 20-30 days later depending on weather, tree canopy and rates used. (V.JONES)

  26. In codling moth mating disruption, how important are the number of point sources of pheromone, relative to the total amount of pheromone?

    The total amount of pheromone appears to be more important as judged by the efficacy of puffers and other massive emitters (which have relatively few point sources per acre and still work). However, that doesn't mean that the number of point sources is not important for dispensers. It is likely there is an interaction between the different behavioral mechanisms operating and possibly differences in the coverage of the orchard when either massive emitters are used or even using fewer dispensers that put out more pheromone (like the Isomate CTT). (V.JONES)

  27. How much pheromone is needed per acre for effective CMMD?

    At this point, we're not really sure. There are some indications from using microencapsulated pheromone sprays, but it probably depends on a range of factors (initial population level, immigration from outside the orchard, use of supplemental sprays, slope of the orchard, wind patterns, etc.). (V.JONES)

  28. Are the chloronicotinyls effective materials for the control of thrips?
    *Do any of the new insecticides provide control of thrips?

    Two questions are important for thrips control on apple with any pesticides: 1) is the material effective and 2) can it be used during bloom, when it will prevent damage? Neither Actara nor Provado have thrips on the apple label since they CANNOT be used during bloom; however, they have thrips elsewhere on the labels for use on other crops, for example, cotton in the case of Actara, and mango in the case of Provado. This indicates that there is some activity against thrips in this class of chemistry, although the target stage may be different. The two other chloronicotinyls, Assail and Calypso, should be much safer to bees, and thus offer at least the potential for testing against thrips. The current Assail label does not list thrips on any crop. I would only consider these materials as having potential as a control for thrips, a potential that will need to be established through further research. (E. BEERS)

  29. Why are campylomma consistently a problem in some apple blocks and not in others?

    This is essentially unknown. While we have studied spray programs, prey population levels, and extra-orchard habitat, we still do not have a good correlation between consistent problems with campylomma and any of these factors. One question that has arisen is the potential effect of dropping Lorsban from the prebloom program. This material is highly toxic to campylomma, and the shorter the interval between application and campylomma hatch (caused by warm weather during this period), the greater the effect will likely be. My theory is that Lorsban may act as a restraining factor on campylomma populations; under optimal conditions, it may eliminate survivors from the front end of the egg hatch so that no bloom-time applications are necessary. Although we state that the prebloom timing is not optimal for control of campylomma the residues of Lorsban are evidently active enough to impact young nymphs emerging near bloom. (Just as a note, I cultivate my campylomma plot on the TFREC orchards by leaving out oil and Lorsban prebloom, and have had up to 60% fruit damage in the absence of other controls). (E. BEERS)

  30. Can the orchard ground cover or surrounding vegetation be changed to enhance bio control?

    In theory, yes. In practice, this has been more difficult to demonstrate. Success has not been very good with the "shotgun" approach -- that is planting nectar sources for adult parasitoids, hoping they show up at the right time, and then conveniently switching to the trees when a pest problem arises. Another caution for some cover crops is that they can also harbor tree fruit pests, and thus create or contribute to a more acute problem. A more refined strategy is specifically engineering the intra- or extra-orchard habitat to provide specific habitat or alternative hosts for parasitoids KNOWN to attack tree fruit pests. For example, by providing a plant host for a leafhopper which overwintered in the correct stage (egg) to support the leafhopper egg parasitoid, Anagrus epos, we might then increase the density of Anagrus to control other pests like the white apple leafhopper. Another example that is currently being researched in Washington involves providing a plant host (wild rose or strawberry) for an alternative insect host (strawberry leafroller) for the leafroller parasitoid (Colpoclypeus florus) so it will then be available to attack our two primary leafroller pests, pandemis and obliquebanded leafrollers. Complicated, but these latter systems have a greater chance of success. (E. BEERS)

  31. What effect do IGRs have on natural enemies?

    As a group, the IGRs tend to be fairly benign toward natural enemies...BUT, like most generalizations, there are exceptions. One that was found recently was the sterilizing effect of Dimilin (diflubenzuron) on Colpoclypeus florus, an important leafroller parasitoid. One of the difficulties with the IGRs is that effects are more likely to be subtle (or sublethal) and go unnoticed unless studied in great detail. (E. BEERS)

  32. What works on rosy apple aphid?

    No silver bullet for this pest, but the chloronicotinyls are probably the best we have currently registered. Rosy apple aphid is listed by name on the Actara label, implied on the Provado label, and the new Assail label is a little vague ("Aphid species may differ in susceptibility..."). Anything you use will probably work better if is applied against small colonies (prebloom or just after bloom); conversely, anything used very late will probably also look good because predators will take them out eventually. One observation, which I feel has merit, is that rosy apple aphids are persisting longer into the growing season than they used to, that is, producing more generations on apple before moving to their summer host. They also seem to be a little more problematic than in the past, although they are still classified as a sporadic pest. (E. BEERS)

Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us