What the ... ?
This is a continuation of my summary of insecticide phytotoxicity information. (See last week's newsletter for Part 1.)
Disclaimers, again: The information I’ve gathered here is for quick reference only, so you must read the labels to find the crop safety of the products. Better yet, do a trial on your own to make sure a new product is indeed safe on your crops.
Plant species with phytotoxic concerns are listed for each product:
Magus (fenazaquin): Use caution when use on roses.
Mainspring Xtra (cyantraniliprole + thiamethoxam): Applications to yellow varieties of honey locust (Gleditsia triacanthos) may cause temporary leaf chlorosis and leaf drop. Also, use on linden or basswood (tilia) is prohibited. These restrictions also appear on Flagship 25WG (thiamethoxam) label.
Malathion 8 Flowable (malathion): Ferns (Boston, maidenhair and pteris), some crassula species and canaert juniper. Spotting or discoloration of fruit or foliage can occur on various crops under high temperature, excessive runoff and other conditions.
Marathon 1% G and Marathon II (imidacloprid): Cannot be applied to linden, brasswood or any tilia species. Not necessarily due to phytotoxicity, but likely for pollinator protection.
M-Pede (potassium salts of fatty acids): Horse chestnut, Japanese maple, mountain ash, cherimoya, bleeding heart and sweetpeas. The label also recommends testing before use on bald cypress, begonia, chrysanthemum, crown-of-thorns (and other euphorbia species), cucumber, ferns, narrow-leaf evergreens, dieffenbachia, fuschia, gardenia, impatiens, jade plant, lantana, ornamental ivy, palms, poinsettia, redbud, river birch, schefflera, zebra plant and some succulents. Flowers of many common ornamentals—including African violet, azalea, rose and orchid—may also be damaged.
Neemix 4.5 (azadirachtin): Comice pears and other sensitive pear varieties, as well as wilted or stressed plants or newly transplanted material prior to root establishment.
Nufarm Chlorpyrifos SPC 4 (chlorpyrifos): Caution when used on azaleas, camellias, poinsettias, rose bushes and variegated ivy.
Orthene TTO 97 Spray (acephate): Huckleberry, Balm of Gilead, cottonwood, Lombardy poplar and Viburnum suspensum. Use caution when used on some chrysanthemum varieties (Albatross, Bonnie Jean, Dixie, Garland, Gem, Iceberg, Pride, Showoff, Statesman, Tally Ho, Westward Ho and Wild Honey) and crabapple varieties (Hopa, Ichonoski, Malus floribunda, Pink Perfection, Red Wine and Snow Cloud). Certain foliage plants—including Bletchum gibbum, Cissus antarctica, Ficus triangularis, Fittonia verchaffeltii, Maranta leuconeura kerchoveana, Pachystachya lutea, Plectranthus australis, Polypodium aureus, Polystichum, Pteris ensiformis and Tolmiea menziesii—may be sensitive.
Pedestal (novaluron): Poinsettias.
Perm-Up 3.2 EC (permethrin): Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Direct contact with blooming plants may cause necrosis on petals.
Pradia (cyclaniliprole + flonicamid): Certain pansy varieties. IR-4’s crop safety trials did not detect injury on pansy and geranium; check the report for varieties.
Pylon and Pylon TR (chlorfenapyr): Dianthus (carnations, pinks and Sweet William), kalanchoe, poinsettia, roses, salvia, zinnia and rhododendrons/azaleas.
Safari 20 SG (dinotefuran): Linden, basswood or other tilia. This is likely for pollinator protection.
Sevin XLR Plus (carbaryl): Boston ivy, Virginia creeper and maidenhair fern. Injury may also occur on Virginia and sand pines, and Early Dawn and Sunrise varieties of strawberries.
Savate (spiromesifen): Geranium (Pelargonium sp.), peperomia, dracaena and rose (variety Classy, Attache and Vogue). Insufficient tolerance information for lily-of-the-Incas (alstroemeria), New Guinea impatiens, bacopa, English ivy, cyclamen, argyranthemum, hydrangea, matthiola, Mexican heather, lobelia, fuchsia, cordyline, neanthebella palm and primula. Do not apply more than 2 fl. oz. per 100 gal. per application cycle to chrysanthemum, Shasta daisy, snapdragon, impatiens, gerbera daisy or marigold.
Shuttle (acequinocyl): Exercise caution when used on certain varieties of impatiens and miniature roses.
Spear-T (GS-omega/kappa-Hxtx-Hv1a): Use caution when dipping geranium, petunia and salvia cuttings.
SuffOil-X (mineral oil): Use caution and reduced dosage on Japanese maple, Amur maple and black walnut in the summer, and on sugar maple and redbud for dormant applications. Oil may remove the glaucous bloom from blue spruces (Colorado and Koster).
Sultan (cyflumetofen): Do not use on plants exhibiting stress symptoms, such as stunting, wilting, leaf burn or abnormal growth. Use an adjuvant to mitigate deposition of spray residue on certain plants, such as poinsettia. Impatiens may be damaged when applied at two or four times the label rates, according to IR-4’s crop safety trials.
Tame 2.4 EC (fenpropathrin): Do not use high gallonage applications to certain chrysanthemum varieties and chrysanthemums and roses with open flowers. Do not mix with Orthene (acephate) when used on poinsettias after bract formation.
TetraCURB MAX (castor oil + rosemary oil + clove oil + peppermint oil): Do not apply on plants under stress or when temperature is 90F or above.
TetraSan 5 WDG (etoxazole): Poinsettia after bract formation.
Triact 70 (clarified hydrophobic extract of neem oil): Flowers of impatiens, fuchsia, hibiscus and rose. Also, ornamental olive trees, some carnation varieties, wilted or stressed plants, or newly transplanted materials prior to root establishment. Applications to poinsettias and cut roses aren't recommended.
Ventigra (afidopyropen): Coleus (Rustic Orange), Ficus benjamina and poinsettia at bract formation. May occasionally cause discoloration to flowers of impatiens and petunia. IR-4’s crop safety summary for afidopyropen indicated that injury may occur on certain cultivars of columbine and dahlia, but additional testing is needed.
I want to direct y’all to Bill Calkins’ Tech On Demand newsletter just in case you don’t subscribe to it. (Why don't you?)
Bill talked about three issues that everyone should be watching out for this time of the year: aphids, impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV). I’m not going to repeat the information Bill has provided about aphids, but certainly check it out since there's valuable information on how to scout for aphids.
A symptom of tomato spotted wilt virus infection on tomato. (Source: Tech On Demand.)
Both viruses are transmitted by thrips, which are getting active now. But thrips aren’t the only way the viruses can get into the greenhouse. Infected plants that are otherwise not showing the typical symptoms of INSV and TSWV (i.e. asymptomatic plants) can also introduce the viruses into the greenhouse and they’ll spread if there are resident thrips. Bill has provided a link to an e-GRO pictoral guide to INSV symptoms from Nora Catlin and Margery Daughtrey of Cornell Extension. Any dudpicious plants should be tested with immunostrips, which are widely available from (for example) Agdia.
Since there’s no cure for viral diseases, it’s very important for you to find and quickly dispose of the infected plants. I would suggest testing the asymptmatic plants in the same batch and dispose plants that are tested positive or (perhaps a bit extreme) all plants in the same batch.
Thrips management is important to prevent INSV and TSWV spread. Start treatment as soon as thrips are found, whether they’re hiding in the flowers or leaves or are stuck on sticky cards. There are options in quickly reducing thrips population. My favorites are Hachi-Hachi SC (tolfenpyrad), Overture (pyridalyl), Pylon (chlorfenapyr), Aria (flonicamid), Mainspring (cyclaniliprole), Tristar (acetamiprid) and tank mix of abamectin + bifenthrin.
I’ll also throw in Conserve (spinosad) or XXpire (sulfoxaflor + spinetoram) since I’m still seeing good efficacy with them despite concerns over resistance to insecticides in IRAC Group 5.
I’m sure you have your own favorite program for thrips; do that early and consistently. And don’t forget biological control. When done consistently, biological control can be effective in preventing a blowout of thrips.
Answer to "What the ... ?"