Treatment Tips for Healthy Garden Mums
April 4, 2022 
White rust on chrysanthemum can spread fast throughout the greenhouse, resulting in serious crop loss. Photo: GGSPro
There are many pest control options when growing garden mums. Various treatments are available to deter diseases, insects, and mites, including options that are pollinator-friendly. The best options for pest control are detailed below (mode of action codes appear in parentheses).
Treatment Options for Foliar Diseases
Chrysanthemum White Rust (CWR): Apply a foliar spray using a strobilurin fungicide while the rooted cuttings are still in the propagation tray. Broadform (7&11), Fame (11), Heritage (11), Mural (7&11), Pageant (7&11), or Orkestra (7&11) are all good options. After planting, preventative foliar sprays only need to be made if weather conditions are forecasted to be favorable for CWR development. Rainy and cool conditions for more than 24 hours would be a reason to make the treatment before the forecasted weather sets in. Daconil WeatherStik* (M5) or Protect DF (M3) are reasonably priced protectants. If CWR is detected in the surrounding area, a second application of a strobilurin is recommended for enhanced protection. Eagle (3) and Avelyo (3) are curative fungicides for rust and should be saved in case CWR is detected in the mum crop.
Additional Foliar Diseases: For overhead irrigated crops or prolonged rainy conditions late in the crop, bacterial leaf spot (Pseudomonas cichorii) and fungal pathogens such as botrytis and aerial rhizoctonia can threaten a garden mum crop. This is most likely to occur later in the crop when the crop canopy is dense and air movement into the center of the plant is limited. For bacterial leaf spot, Companion Maxx, Cease, Stargus, and Triathlon BA can be used as preventatives. At the first sign of bacterial disease, a tank mix of a copper bactericide (M01) such as Badge, Camelot O*, Grotto*, Kalmor, Phyton 35*, etc. and a mancozeb such as Protect DF (M3) should be applied. KleenGrow (NC) has also shown good efficacy versus bacterial leaf spot. An important part of fighting bacterial leaf spot is to avoid overhead irrigations if possible. Make note of vulnerable mum varieties and work to replace them in the mum program. Aerial rhizoctonia often occurs with botrytis, so we recommend fungicides that control both. Options include Affirm (19), Broadform (7&11), Daconil WeatherStik* (M5), Medallion (9), Mural (7&11), Pageant (7&11), Palladium (9&12), Orkestra (7&11), or Spirato GHN (9)
*Avoid treating open blooms with these products.
Rhizoctonia is a fungal pathogen that causes web blight on chrysanthemum.
Treatment Options for Root and Crown Diseases
Fusarium: There are no curative fungicides for this disease, but the following soil drenches can be applied preventatively: 3336 or other properly labeled t-methyl products (1), Mural (7&11), Heritage (11), Medallion (9), and Spirato GHN (9). For a thorough discussion of fusarium in garden mums, request the bulletin titled, “Defense Against Fusarium Wilt in Chrysanthemum” by Joanne Lutz, GGSPro.
Pythium: Drench soon after transplanting with Segway O (21). RootShield Plus G (NC) can be pre-incorporated into the soil mix without being damaged by Segway O. RootShield Plus WP (NC) can be applied as a soil drench within a week after the Segway O drench if desired. From that point on, shift to a “see and treat” protocol. If another drench is required, one of the etridiazole products could be used to rotate with Segway O-Banrot (1&14), Terrazole L (14) or Truban (14).
Insecticidal Drenches: Due to bee safety concerns with neonicotinoid drenches, e.g., Flagship (4A), Marathon (4A) and generics, Safari (4A), GGSPro advises that they only be applied during the first two weeks after transplanting so that the bee hazard diminishes before open bloom occurs. Kontos (23) applied as a drench is effective against many garden mum pests, including aphids, leafhoppers, leafminers, spider mites, thrips, and whiteflies. Mainspring GNL (28) when applied as a drench is effective against aphids, beetles, caterpillars, leafhoppers, leafminers, thrips, and whiteflies. Endeavor (9B) drenches are an option for aphid control.
Insecticidal Spray Guide
Some of the products listed below have bee safety boxes that contain important information regarding minimizing potential hazards to bees and other pollinators. Read and follow all label instructions.
Aphids: Altus (4D), Aria (29), Endeavor (9B), Kontos (23), Pradia (28&29), TriStar (4A), Ventigra (9D), and XXpire (4C&5). Rycar (9B) can only be used on mums grown in greenhouses.
Caterpillars: Acelepryn (28), Conserve (5), DiPel Pro DF (11A), Mainspring GNL (28), Pedestal (15), Pradia (28&29), Sarisa (28), TriStar (4A) and XXpire (4C&5). Pedestal can only be used in greenhouses in New York.
Leafhoppers: Altus (4D), Kontos (23), Sanmite SC (21A), and TriStar (4A).
Leafminers (inc. blotch type)-Adult stage: Avalon Golf & Nursery (3A) and Conserve (5). Larval stage: Avid (6), Citation (17), Minx 2 (6), Pradia (28&29), Sarisa (28), and TriStar (4A).
Spider Mites: Akari (21A), Avid (6), Magus (21A), Minx 2 (6), Sanmite SC (21A), Savate (formerly Judo) (23), Shuttle O (20B), and Sultan (25).
Thrips: Avid (6) or Minx 2 (6) tank mixed with an approved azadirachtin IGR (UN); Mainspring GNL (28), Pedestal (15), Pradia (28&29), Sarisa (28) and TriStar (max label rate only) (4A). GG
Author’s note: Whenever practical, GGSPro encourages growers to scout and rely on a “see and treat” approach to disease, insect, and mite control. Not all products are registered in all states. Some pesticides are restricted use in some state or regions and not others. It is the responsibility of the applicator to read and follow all label directions. Products other than those listed may also be safe and effective.
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