July 1, AppleTalk Call Summary

AppleTalk Conference Call Summary
Tuesday, July 1st, 2014, 8:00 – 9:00 a.m.
Presenter: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

July 1st Call download: Click Here

Weather recap minute 1:20
June’s average temperature is one to two degrees above normal for sites from Green Bay to the Twin Cities. In southern Wisconsin temperatures are close to five degrees above normal. Precipitation is an inch or more above the monthly average.

Managing tree health after severe weather 3:00
Hail damage: fruit
Early season fruit is less susceptible to damage as wounds heal quickly, preventing entry points for pathogens. Injury occurring later in the season, e.g., late July to harvest, is of greater concern as damaged tissue will quickly lead to rots and decay. Although the risk of fruit rots developing are reduced at this time in the season, they can still occur, and scouting for them is valuable in designing a fungicide plan for the remainder of the season. It is difficult to differentiate between rots when they are small, yet as they grow and begin to sporulate they are easier to identify. Black and white rot infections have black pustules and bitter rot has orange to pink pustules surrounding a circular lesion. Protectant fungicides present on fruit tissue before the storm will reduce the possibility of infection in the event of hail. Fire blight bacteria that enter wounded fruit is not likely to infect woody tissue.

Damage: woody tissue
Woody tissue damaged by hail is more susceptible to fire blight before the terminals have set. Fire blight is less likely to spread once the trees have matured. If severe weather results in damage streptomycin can be applied within 24 hours of the storm. If resources are limited focus on young, first and second year trees that have the greatest potential for damage. Fire blight is showing as shoot blight, not blossom blight, in majority of orchards which suggests that if copper was applied in the spring it did not offer effective control (review April 29 AppleTalk). When blight develops, it is recommended to, prune or snap out infected shoots twelve inches below symptoms, if on small or unfeathered trees remove what is feasible; may require removal of the whole tree. It is critical to control fire blight while trees are actively growing.

Summer diseases and disease modeling 19:00
It is suggested to track rainfall from the date of the petal fall fungicide application until two inches, cumulative, of rain has fallen. At that point begin calculating leaf wetness hours. If two inches of rain has not fallen, begin calculating leaf wetness hours after 21 days. Mark date of either scenario and track leaf wetness hours to 185. It is important to apply/reapply fungicides for summer disease fungicides before 185 leaf wetness hours have been accumulated to protect against summer diseases. Sooty blotch and fly-speck can develop on stored apples if this criteria is not meet. LWH from last fungicide application to harvest is included in this suggestion.

Fungicides for sooty blotch and fly-speck include: sterol inhibitors, i.e., Indar (fenbuconazole) and Inspire Super MP (difenoconazole, cyprodinil), and Topsin M (thiophanate-methyl). Fungicides for fruit rots: captan and strobilurins, i.e., Flint (trifloxystrobin) and Sovran (kresoxim-methyl). Differentiate between black/ white rot and bitter rot to determine what fungicides to apply.
Refer to June 23 and 30 Scaffolds Fruit Journal below.

Codling moth 38:45
With 15-20% of eggs remaining from first generation to hatch, trap counts will begin decreasing. If trap catches start to build in coming weeks check degree days from first biofix to verify the start of second generation. 500-650 DD peak of first generation egg hatch. 1000 DD expected end of first generation activity.

Japanese beetle 39:40
Japanese beetle are beginning to emerge in raspberries along Illinois and Wisconsin state line and in apples near Eau Claire County. Under favorable conditions beetles can quickly move into new locations. After the first few years of introduction, populations grow exponentially and quickly become the predominant pest. Once established, the population decrease as a result of biological control. Numbers have decreased over last few years due to environmental factors, e.g., heat and drought of 2012, reducing food sources for larvae, such as, roots of grasses. As a result there are less egg laying adults and developing young in 2013. Favorable conditions last summer and so far this summer may suggest and increase in populations.

It is not suggested to trap for Japanese beetle, if monitoring scout in raspberries or locations where beetles have been spotted early in the season. Chemical control is only effective when populations are low and immigrating into the orchard. Control is very difficult to achieve when large populations are established. Beetles release an aggregation pheromone to attract more beetles, therefore dying beetles are still attracting others. When timing an application note the daily location of beetles, typically in trees during the day and move to orchard floor at night.

Apple maggot 53:35
Trapping and monitoring guidelines
For orchards without a history of apple maggot damage it is recommended to hang three red ball traps per ten acres. Locate traps along perimeter where wild hosts are present. It is important to have traps visible so adult flies can detect them when traveling into the orchard. As the adults travel into the orchard they distinguish host trees by shape, when they are within three to five feet of the tree they can pick out an apple. To bait or not to bait? Threshold changes from one fly (without volatile) to five flies with an apple volatile. Pros and cons exist for both technique. Baited traps located on the perimeter can pull flies into the orchard. A low density of unbaited traps can result in a false negatives. The risk of false negatives can be reduced by increasing trap density. Monitor early season varieties that exist on the interior of block separately. These varieties can harbor resident populations that may not affect neighboring varieties. If pressure has been high in the past, use bait to reduce chances of false negatives, the fear of bringing in additional flies is negligible. Always apply more tangle trap then not enough.
Refer to June 30 Scaffolds Fruit Journal below.

Additional articles and resources
• Scaffolds Fruit Journal. June 23, 2014.
• Scaffolds Fruit Journal. June 30, 2014.