This model counts accumulated rain and number of days from last spray to estimate when insecticide coverage is no longer sufficient to kill apple maggot flies.\u00a0 This is the recommended date to clean off apple maggot traps and begin counting trap captures again, comparing the total cumulative average caught per trap against the treatment threshold.<\/p>\n
The standard threshold for unbaited red sphere traps is a cumulative average of 1-2 AM fly per trap.\u00a0 For traps combined with a fruit odor-bait capsule, the threshold is a cumulative average of 5 AM trap.\u00a0 At least three traps per block should be used to calculate the average.<\/p>\n
The “old rule” for the duration of residual protection from a full-dose Imidan or synthetic pyrethroid insecticide with a *** “Good” rating in the New England Tree Fruit Management Guide was when one of the following conditions was met:<\/p>\n
2 inches of cumulative rain within the first 10 days after application, That rule was not deemed appropriate for use with insecticides having shorter residual or lower efficacy rating against apple maggot, such as Delegate, spinosad (Entrust), Asana, Avaunt, or carbaryl (Sevin) products.<\/p>\n Each insecticide option for AM control has different characteristics that affect the duration of control after a full-dose, good-coverage application.\u00a0 Some of the key factors are inherent toxicity of the insecticide to the pest; the persistence of residual protection in the absence of rain; the ability of residual protection to resist rain wash off; the ability of the chemical to penetrate into plant tissues for curative activity against eggs.<\/p>\n In a June 2018 Michigan State University Extension article, Rainfast characteristics of insecticides on fruit<\/a> (Michigan State University MSU Extension), Dr. John Wise reported results from tests with a rain tower to simulate different amounts of rain at one and seven days after application, followed by tests of the residual coverage several key fruit insect pests, including codling moth on apple, but not apple maggot fly.\u00a0 Those findings provided the impetus for devising best guess values for residual efficacy against apple maggot fly on apple.<\/p>\n The following summary table leaves out many of the details that were considered in devising rules for the number of days and cumulative rain since the application.\u00a0 For example, the \u201cRain resistance\u201d rating summarizes six different ratings for three different rain amounts times two types of plant tissue (foliage and fruit).\u00a0 Because of those omissions, the tentative rule may not seem to fit with the other values shown for that material.\u00a0 In those cases, other factors such as inherent toxicity to the pest not shown in the table influenced the duration guideline.<\/p>\n Duration guidelines were also based on efficacy ratings from:<\/p>\n Class: Organophosphate PHI: 7 days<\/td>\n Days 7-14, up to 1\u201d rain<\/p>\n 15 days maximum even if no rain.<\/p>\n Notes:\u00a0 Long history of effective AM control.\u00a0 Poor rain resistance compensated by high efficacy against pest.\u00a0 Long residual in absence of rain.\u00a0 Customer concerns about OPs.<\/td>\n<\/tr>\n Class: Neonicotinoid PHI: 7 days<\/p>\n Minimum respray interval:\u00a0 12 days<\/p>\n Application limit:<\/td>\n 14 days maximum even if no rain.<\/p>\n Notes:\u00a0 Proven effective AM control. Lower inherent toxicity to AM than Imidan compensated by rain resistance, and repellence and curative activity against eggs. Customer concerns about neonic impacts on honeybees more relevant to neonics in the nitro group.\u00a0 Assail is not in that subgroup, and has lower acute toxicity to honeybees, but customers concerned about neonics may not be aware of such details.<\/td>\n<\/tr>\n Class: Pyrethroid PHI: Baythroid<\/strong> 7 10 days maximum even if no rain.<\/p>\n Notes:\u00a0 Repeated use of pyrethroids may flare populations of mites, woolly apple aphid, San Jose scale or other pests normally kept in check by biocontrol.<\/td>\n<\/tr>\n Class: Diamide PHI: 3 days<\/td>\n 10 days maximum even if no rain.<\/p>\n Notes:\u00a0 Phytotoxicity concerns.\u00a0 Do not tank-mix with strobilurins, copper or captan fungicides. Application within 7-days of these materials, other EC pesticides, or spreader\/penetrant adjuvants may increase risk of crop injury.<\/td>\n<\/tr>\n Class: Pyrethroid PHI: 21 days<\/td>\n Days 7-10, up to 0.5\u201d rain<\/p>\n 10 days maximum even if no rain. Notes:\u00a0 I do not have data to justify separating Asana out from other pyrethroids, but have done so based on concern that it may be more heat-sensitive than 2nd-generation pyrethroids.<\/td>\n<\/tr>\n Class: Organophosphate PHI: 21 days<\/td>\n Entrust<\/strong> (spinosad).<\/p>\n Class: Spinosyn PHI: 7 days<\/td>\n Day 8-9, up to 0.5\u201d rain<\/p>\n 9-day maximum even if no rain.<\/p>\n Notes:\u00a0 MI Extension rates Delegate and Entrust as for suppression only against AM, suggesting that these materials are not reliable against high AM pressure.<\/td>\n<\/tr>\n Class: Carbamate PHI: 3 days<\/td>\n Day 8-9, up to 0.5\u201d rain<\/p>\n 9-day maximum even if no rain.<\/p>\n Notes:\u00a0 While carbaryl acts as a thinner during the fruit set period, it will not have a thinning effect when used in July-August.<\/td>\n<\/tr>\n Class: Diamide PHI: 5 days<\/td>\n Days 7-10, up to 0.5\u201d rain.<\/p>\n 10 days maximum even if no rain.<\/p>\n Notes:\u00a0 MI lists interval as 10-14, but with Fair rating and for suppression only.\u00a0 Apparently, it lasts well, but has less inherent toxicity against apple maggot than higher ranked alternatives.<\/td>\n<\/tr>\n Class:\u00a0 Oxadiazine PHI: 14 days<\/td>\n Days 7-10, up to 0.5\u201d rain<\/p>\n 10 days maximum even if no rain.<\/p>\n Notes:\u00a0 MI Extension gave Avaunt a Poor rating against AM.<\/td>\n<\/tr>\n Class: Neonicotinoid PHI: 7 days<\/td>\n No IRAC class<\/p>\n PHI: 0 days (but application near harvest would exacerbate visible residue)<\/td>\n Class: Spinosyn PHI: 0 days<\/td>\n This attempt to represent the information on each material as weather-based rules is intended to help growers make decisions about insecticide selection and respray intervals and to update the apple maggot respray interval tables in Ag-Radar.\u00a0 Keep in mind these are just best guesses at summary extensive data into simple rules.\u00a0 Only single active ingredient products are listed.\u00a0 PHI = preharvest interval for apples.<\/p>\n The guidelines shown in the Ag-Radar respray tables assume a moderate level of apple maggot pressure.\u00a0 Once an insecticide application has been depleted by the number of days or rain, clear AM traps and begin counting from zero towards the threshold to see if\/when retreatment is needed.\u00a0 More stringent respray guidelines may apply where pest pressure is abnormally high.<\/p>\n
\nor
\n<\/em><\/strong>1.5 inches of cumulative rain from 10-14 days after application,\u00a0
\n<\/em>or
\n<\/em><\/strong>14 days maximum even if no rain.<\/p>\n\n
\nCornell University Cooperative Extension.<\/li>\n
\nVirginia, West Virginia, and the University of Maryland Extension.<\/li>\n
\nJuly 13, 2010 by John Wise, David Epstein, Larry Gut, and Lu\u00eds Teixeira, Michigan State University Extension<\/li>\n<\/ul>\n\n\n
\n Insecticide<\/strong><\/td>\n Efficacy rating<\/strong><\/td>\n Days residual<\/strong><\/td>\n Plant pene-tration<\/strong><\/td>\n Rain resistance<\/strong><\/td>\n Duration of protection estimate \u00a0\u00a0<\/strong><\/td>\n<\/tr>\n<\/thead>\n\n \n Imidan<\/strong><\/p>\n
\nIRAC 1B<\/p>\nGood to Excellent<\/td>\n 14+<\/td>\n Surface<\/td>\n Low<\/td>\n Days 1-6, up to 1.5\u201d rain.<\/p>\n \n Assail<\/strong><\/p>\n
\nIRAC 4A<\/p>\nGood to Excellent<\/td>\n 14<\/td>\n Trans-laminar & Acropetal<\/td>\n Moderate<\/td>\n Days 1-14, up to 1\u201d rain.<\/p>\n \n Pyrethroids<\/p>\n
\nIRAC 3A<\/p>\n
\nDanitol <\/strong>14, Mustang<\/strong> Maxx<\/strong> 14 Warrior<\/strong> 21<\/td>\nGood<\/td>\n 7-10<\/td>\n Cuticle pene-tration<\/td>\n Moderate<\/td>\n Days 1-10, up to 1\u201d rain.<\/p>\n \n Exirel<\/strong><\/p>\n
\nIRAC 28<\/p>\nFair to Good<\/td>\n 10<\/td>\n Trans-laminar<\/td>\n Moderate-High<\/td>\n Days 1-10, up to 1\u201d rain.<\/p>\n \n Asana<\/strong><\/p>\n
\nIRAC 3A<\/p>\nFair to Good.<\/td>\n 7-10<\/td>\n Cuticle pene-tration<\/td>\n Moderate<\/td>\n Days 1-6, up to 1\u201d rain.<\/p>\n
\nAsana may be less effective above 80\u00ba F.<\/p>\n\n Diazinon<\/strong><\/p>\n
\nIRAC 1B<\/p>\nFair to Good<\/td>\n ? but less than Imidan<\/td>\n Surface<\/td>\n Low<\/td>\n 4-day Restricted Entry Interval.\u00a0 Not enough information to devise rain guideline.<\/td>\n<\/tr>\n \n Delegate<\/strong> (spinetoram),<\/p>\n
\nIRAC 5<\/p>\nFair<\/td>\n 7-9<\/td>\n Trans-laminar<\/td>\n Moderate-High<\/td>\n Days 1-7, up to 2\u201d rain.<\/p>\n \n Sevin<\/strong> (carbaryl)<\/p>\n
\nIRAC 1A<\/p>\nFair<\/td>\n 7-9<\/td>\n Cuticle pene-tration<\/td>\n Moderate<\/td>\n Days 1-7, up to 2\u201d rain.<\/p>\n \n Altacor<\/strong><\/p>\n
\nIRAC 28<\/p>\nFair<\/td>\n 10<\/td>\n Trans-laminar<\/td>\n Moderate-High<\/td>\n Days 1-6, up to 1\u201d rain.<\/p>\n \n Avaunt<\/strong><\/p>\n
\nIRAC 22<\/p>\nFair<\/td>\n 7-10<\/td>\n Cuticle pene-tration<\/td>\n Moderate<\/td>\n Days 1-6, up to 1\u201d rain.<\/p>\n \n Admire Pro<\/strong><\/p>\n
\nIRAC 4A<\/p>\nFair<\/td>\n ? but less than Assail<\/td>\n Trans-laminar & Acropetal<\/td>\n Moderate<\/td>\n Notes:\u00a0 Admire is a member of the neonic subgroup driving concerns about impacts on honeybees.\u00a0 Not enough information to devise rain guideline.<\/td>\n<\/tr>\n \n Surround<\/strong><\/p>\n Fair<\/td>\n Varies with rain<\/td>\n Surface<\/td>\n Low<\/td>\n Requires reapplication after about 0.5\u201d rain, as judged by thorough visible coverage.\u00a0 Deters but does not kill AM so coverage must be maintained through egglaying season. Organically certifiable.<\/td>\n<\/tr>\n \n GF-120<\/strong><\/p>\n
\nIRAC 5<\/p>\nFair<\/td>\n 7-14<\/td>\n Works as bait and kill.<\/td>\n <\/td>\n Requires special applicator equipment.\u00a0 Organically certifiable.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n