Treatment Tips for Healthy Garden Mums


White rust on chrysanthemum can quickly spread throughout the greenhouse, causing serious crop loss. Photo: GGS Pro

There are many pest control options when growing garden mums. Various treatments are available to deter disease, insects and mites, including pollinator-friendly options. The best pest control options are detailed below (mode of action codes appear in parentheses).

Treatment options for leaf diseases

Chrysanthemum white rust (CWR): Apply a foliar spray using a strobilurin fungicide while 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 should only be done if predicted weather conditions are favorable for CWR development. Rainy and cool conditions for more than 24 hours would be a reason to do the treatment before the expected weather sets in. Daconil WeatherStik* (M5) or Protect DF (M3) are reasonably priced protectors. If CWR is detected in the surrounding area, a second application of strobilurin is recommended for added protection. Eagle (3) and Avelyo (3) are rust curative fungicides and should be saved in case CWRs are detected in the parent crop.

Other leaf diseases: For crops irrigated by sprinkling or prolonged rainy conditions at the end of the crop, bacterial leaf spot (Pseudomonas cichorii) and fungal pathogens such as botrytis and aerial rhizoctonia can threaten a crop of garden chrysanthemums. This is more likely to occur later in the crop when the canopy is dense and air movement towards 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 illness, 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) also showed good efficacy against bacterial leaf spot. An important part of controlling bacterial leaf spot is to avoid overhead irrigations if possible. Take note of vulnerable mother varieties and strive to replace them in the mother program. Airborne 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 flowers with these products.

Chrysanthemum, Rhizoctonia Web Blight

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 preventively: 3336 or other properly labeled t-methylated products (1), Mural (7&11), Heritage (11 ), Medallion (9) and Spirato GNH (9). For an in-depth discussion of Fusarium in garden chrysanthemums, request the newsletter titled “Defense against Fusarium wilt in Chrysanthemums” by Joanne Lutz, GGSPro.

Pythium: Dip shortly after transplanting with Segway O (21). RootShield Plus G (NC) can be pre-incorporated into the soil mix without being damaged by the Segway O. RootShield Plus WP (NC) can be applied by soil drench within one week of Segway O dipping if desired. From this point, switch to a “see and treat” protocol. If further watering is needed, one of the Etridiazole products can be used alternately with Segway O-Banrot (1&14), Terrazol L (14) or Truban (14).

Insecticidal dips: Due to bee safety issues with neonicotinoid sprays, e.g. Flagship (4A), Marathon (4A) and the generics, Safari (4A), GGSPro advises applying them only for the first two weeks after the transplanting so that the danger to bees decreases before an open bloom occurs. Kontos (23) applied by drench is effective against many pests of garden chrysanthemums, including aphids, leafhoppers, leaf miners, spider mites, thrips and whiteflies. Mainspring LNG (28) when applied as a drench is effective against aphids, beetles, caterpillars, leafhoppers, leafminers, thrips and whiteflies. Endeavor sprinklers (9B) are an option for controlling aphids.

Insecticide Spray Guide

Some of the products listed below have bee safety boxes that contain important information regarding reducing potential risks to bees and other pollinators. Read and follow all label directions.

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 greenhouse grown chrysanthemums.

The caterpillars: Acelepryn (28), Conserve (5), DiPel Pro DF (11A), Mainspring LNG (28), Pedestal (15), Pradia (28&29), Sarisa (28), TriStar (4A) and XXpire (4C&5). The pedestal can only be used in greenhouses in New York.

Leafhoppers: Altus (4D), Kontos (23), Sanmite SC (21A) and TriStar (4A).

Miners (inc. Stain 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 tank (6) or Minx 2 (6) mixed with azadirachtin IGR approved (UN); Mainspring LNG (28), Pedestal (15), Pradia (28&29), Sarisa (28) and TriStar (maximum tag rate only) (4A). GG

Author’s note: Whenever possible, GGSPro encourages growers to spot and use a “see and treat” approach to controlling diseases, insects and mites. Not all products are registered in all states. Some pesticides are restricted in some states or regions and not in others. It is the responsibility of the applicator to read and follow all label instructions. Products other than those listed may also be safe and effective.



Comments are closed.