FINISHING GUIDE cont.
Root Rots Healthy roots are the first line of defense against rootzone diseases. The loss of roots early in the crop will significantly limit nutrient loading and plant size later in the crop cycle. Saturated soil, extreme wet-dry cycles or high salt levels will damage the roots, making them more susceptible to disease infection. Failure to control root rot can result in stunted plants. Preventative treatment for Pythium and other root diseases is recommended every 4 weeks. Pests and Diseases Integrated pest management (IPM) is the best defense against pests and diseases that affect mums. Scout crops daily for signs of pests or pathogens when assessing daily watering and feeding needs and review weekly bug counts to assess changes in pressure over time. Preventative management, early detection and swift reaction to pest and disease presence will minimize risk and subsequent crop losses. Growers should also scout for foliar diseases, including bacterial leaf spot and botrytis. Chrysanthemum white rust (CWR) is a USDA quarantinable pathogen and preventative fungicides should be applied to crops grown in higher-risk areas. Media pH Track pH throughout production using a 2:1, SME or PourThru method. • Low pH can cause iron (Fe) and/or manganese (Mn) to become overly available to plants in the growing media. Plants will take up excessive amounts of both, resulting in Fe/Mn toxicity. Typical symptoms include discoloration, dark splotching and necrosis on older growth. Correct low pH using a flowable lime product and adjust feed program to include a more basic fertilizer to help buffer media pH changes. • High pH reduces availability of Fe and Mn and can result in deficiency symptoms, including chlorosis, stunting of young shoots and necrosis (in severe cases) on upper foliage.
Ethephon (Florel, Collate) Ethephon (Florel, Collate) can be used to promote branching, prevent premature budding and delay flowering. Apply early in the crop cycle at a rate of 300-500 ppm. Effectiveness varies by variety. • Spray early or late-day, as slow dry time maximizes uptake and response. • Use low alkalinity (<60 ppm) water or increase ethephon (Florel, Collate) rate. • Reduce spray solution to pH <4 before adding ethephon (Florel, Collate). • Don’t pour ethephon (Florel, Collate) directly into tank. Use a funnel or put ethephon (Florel, Collate) in bag and empty into tank. • “Sprench” to cover plants. Common Growing Issues Premature Budding & Crown Bud Formation Several occurrences of cool nights (colder than 60°F/15°C) in late Spring and early Summer can trigger premature bud formation. This is not desirable and can cause plants to finish too small. If small buds are visible in the early stages of production, plants usually can still develop normally. Premature bud set can be minimized by limiting stress, applying adequate fertilizer amounts (fertility levels should be high) and not allowing plants to wilt. Early applications of 500 ppm Ethephon (Florel, Collate) 1 week after planting or immediately prior to a cold front passing through your area can help minimize premature bud set by helping to promote vegetative growth but does not abort buds once formed. Heat Delay Average daily temperature dictates the rate of development of a crop, but high night temperatures can cause heat delay. When night temperatures exceed 85°F/30°C, flowering cannot be initiated. Heat delay can affect the bloom date by up to 3 weeks. Night temperatures from July 20 until August 5 are the most critical for natural season mums. Some varieties are more sensitive than others.
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