Managing Spider Mites in Almonds David Haviland Entomology Farm Advisor UC Cooperative Extension, Kern Co.
Major influences on spider mites Spider mite biology Biological control Host and environment Chemical controls
Spider Mite Biology Feeds primarily on the leaves Reproduces very quickly Can cause defoliation Results in sunburn Effects on yield assumed but not well documented
Biological Control Sixspotted thrips Stethorus (ladybird beetles) Predatory mites Minute pirate bugs Lacewing larvae
Sixxpotted thrips Scolothrips sexmaculatus Larvae yellowish, cilindrical Adults with 6 spots Both are predacious on mites Can provide compete control of spider mites Often arrive late, since no alternate food source in the spring
Spider Mite Destroyer Stethorus picipes Adults and larvae each consume about one-half dozen mites per day At warm temperatures the spider mite destroyer can complete one generation from egg to adult in about three weeks. Females typically live one to three months, during which they lay about 1 to 2 eggs
Western Predatory Mite Galendromus (Metaseiulus) occidentalis Teardrop shaped, clear to red Most dependable predator Can complete life cycle in 7 days Can provide compete control of spider mites Often arrive late, since no alternate food source in the spring
Release recommendations Galendromus occindentalis For most crops Survive between 6 and 12 F Tolerate how humidity Release between 2,5 and 5, mites per acre at first sign of mites Release more if later in the season Repeat applications may be necessary Usually come on bean plants or in a bottle with a carrier Mites should be spread out evenly Therefore it takes time to do releases, and mites are delicate
Host and Environment- Growing conditions favorable to mites Average almond yields ~3, lbs/ac Dusty conditions ~6-1 inches rain per year No rain May to harvest Deficit irrigation at harvest Hot conditions Average high of 99 F in July and Aug
Integration- IPM Strategy Monitor for spider mites weekly Monitor for natural enemies weekly Don t starve them, don t kill them Evaluate treatment thresholds 25% presence if no predators ~4% presence if predators are present Take into account other considerations Temperature, plant stress, free rides, time of year Comparison to previous week Treat if needed Conserve biocontrol, avoid abamectin if sixspotted thrips is present Good coverage, 2 mph, 1-2 gpa, 1% oil
Chemical Control- principal miticides IRAC # a.i. Name Mode of action 6 abamectin Agri-Mek 1A hexythiazox clofentezine 6 abamectin Agri-Mek clofentezine Apollo 1B 1A hexythiazox etoxazole Onager Zeal 1B etoxazole Zeal Onager Apollo 12C propargite Omite Avermectin contact or ingestion toxin that paralyzes juveniles and adults; death by starvation Growth Regulator growth regulator of mite eggs and some nymphs, adults lay sterile eggs Avermectin contact or ingestion toxin that paralyzes juveniles and adults; death by starvation Growth Regulator contact toxin on eggs; inhibits molting of juveniles; adult females produce sterile eggs Growth Regulator growth regulator of mite eggs and some nymphs, adults lay sterile eggs Growth Regulator contact toxin on eggs; inhibits molting of juveniles; adult females produce sterile Energy eggs metabolite- contact toxin to juveniles and adults by inhibition of ATP synthesis METI III contact toxin on all stages; inhibits electron transport 12B fenbutin-oxide Vendex Energy metabolite contact toxin to juveniles and adults by inhibition of ATP synthesis 2D bifenazate Acramite 12C propargite Omite Energy metabolite- contact toxin to juveniles and adults by inhibition of ATP synthesis Vigilant METI in III the contact mitochondria toxin to eggs, juveniles and adults; inhibits electron transport in the 2B acequinocyl Kanemite fenpyroximate Fujimite mitochondria 2D bifenazate Acramite METI III contact toxin on all stages; inhibits electron transport in the mitochondria fenazaquin Magister the mitochondria 21 fenpyroximate Fujimite METI I contact toxin on all stages; inhibits electron transport in the mitochondria Lipid Synthesis Growth Regulator contact on all mite stages by inhibiting lipid biosynthesis; 23 spirodiclofen Envidor most effective on juveniles 25A cyflumetofen Nealta METI inhibiting II - contact toxin lipid on biosynthesis; all stages; inhibits most electron effective transport in on the juveniles mitochondria 21A 23 spirodiclofen Envidor METI I contact toxin on all stages; inhibits electron transport in Lipid Synthesis Growth Regulator contact on all mite stages by 25A cyflumetofen Nealta METI II - contact toxin on all stages; inhibits electron transport in the mitochondria
1,4 1,2 Almond Trial- hull split 213- Shafter, CA UTC g Oil Mean (±SE) Mite-days 1, 8 6 4 abcd Miticides def abc fg Pyrethroids efg def cdef bcde 2 abc ab a abc ab a Acramite Envidor Fujimite Grandevo Magister Nealta Onager Vigilant Zeal + Oil Asana Brigade Danitol Warrior II Oil Untreated Check All miticides included 1% 415 oil
Good Miticide Control Plum trial, Kern County, Trial treated mid-june, photo taken mid-july 26
Coverage Drive speed- affects air displacement in the tree 2 mph is desireable Water volume- 1 (early season) to 2 (late season) GPA Fan speed Enough to displace air in tree, but not blow product through to the next row (wind sheer and boundary layer issues) Nozzle types Consider air induction nozzles for higher elevations
Effects of miticides on predators general statements (verdict still out on some) Thrips Agri-Mek Agri-Mek very toxic Mites Agri-Mek Onager Zeal Envidor Acramite Fujimite Kanemite Desperado Ecotrol Moderate+ Moderate Toxic (sterilized) Moderate + Soft to Moderate Toxic (contact) Moderate Toxic (contact) Unknown
Case study- Wasco 216
Start sampling- March Case study- Wasco 216 Rain event, leaves washed, trees getting extra water Leaf hardening First NOW hull split spray, Leaves 1% infested, 1 predator/2 leaves, grower knows a second hull split spray will be in 2.5 weeks, Heat wave as water is being pulled One week to 2 nd hull split spray, 2% leaves infested, some predators, pops rising, time to write a rec. Second NOW spray, leaves 33% infested, last chance to spray before harvest, treat with product safe to predators
Mites per leaf 18 Shafter 1.2 Edison McFarland 2 16 1 14 15 12.8 1 8.6 1 6.4 4 5.2 2 Mites per leaf 216 Case Studies Mites/leaf Mites/leaf Mites/leaf Mites per leaf
Mites per leaf 18 Shafter 1.2 Edison McFarland 2 16 1 14 15 12.8 1 8.6 1 6.4 4 5.2 2 Mites per leaf 216 Case Studies Mites/leaf Mites/leaf Mites/leaf Mites per leaf
Thrips per card 18 Shafter 1.2 Edison McFarland 2 16 1 14 15 12.8 1 8.6 1 6.4 4 5.2 2 3 Mites/leaf Mites/leaf Mites/leaf 1 6 25 5 8 2 4 6 15 3 4 1 2 5 1 2 7-Jul 14-Jul 21-Jul 28-Jul 4-Aug 11-Aug 18-Aug Thrips/card Thrips/card Thrips/card Mites per leaf Mites per leaf Thrips per card 216 Case Studies Mites per leaf Thrips per card
Sixspotted thrips 7 days 174 thrips
Thrips per card Mites per leaf 18 16 14 12 1 3 25 2 15 1 Stethorus per card 5 8 6 4 2 Mites/leaf 4 35 3 25 2 15 1 5 Shafter 1.2 Edison McFarland 2 Thrips/card Mites per leaf Thrips per card Stethorus per card 1.8.6.4.2 6 5 4 3 2 1 4.5 3.5 2.5 1.5.5 216 Case Studies Mites/leaf 7-Jul 14-Jul 21-Jul 28-Jul 4-Aug 11-Aug 18-Aug 4 3 2 1 Thrips/card Mites per leaf Thrips per card Stethorus per card 15 1 5 1 8 6 4 2 Mites/leaf Thrips/card 9 8 7 6 5 4 3 2 1 Stethorus/card Stethorus/card Stethorus/card
Integration- IPM Strategy Monitor for spider mites weekly Monitor for natural enemies weekly Don t starve them, don t kill them Evaluate treatment thresholds 25% presence if no predators ~4% presence if predators are present Take into account other considerations Temperature, plant stress, free rides, time of year Comparison to previous week Treat if needed Conserve biocontrol, avoid abamectin if sixspotted thrips is present Good coverage, 2 mph, 1-2 gpa, 1% oil
Thank you