May be symptomless in poinsettias. Yellowing develops between the veins of mid and lower leaves. They need a minimum temperature of 13-15°C (55-59°F). Later, stunted plants defoliate, flower prematurely, and die. MED Whitefly). While there are numerous Pythium species that infect a wide variety of greenhouse ornamentals, Pythium aphanidermatum is the most common pathogen found on poinsettias in late summer and fall. Apply a fungicide to protect plants. JavaScript seems to be disabled in your browser. Heat and vent to reduce humidity. poinsettias in recent years. Plants that are allowed to get too dry will wilt and also drop leaves. It is a Gram-positive bacterium, very different from the Xanthomonas that causes angular leaf spots and the Dickeya and Pectobacterium species that cause cutting rots. Grafting Techniques for Greenhouse Tomatoes. In addition to biotic agents, improper fertilization practices can cause symptoms in poinsettias. Use only sterile soil and clean tools, and hang us hose ends. They can be found either on the plant or soil surface. Defoliation and death of branches occur above cankers that girdle stems. Poinsettias: Disease Prevention and Control. A number of other less common biotic and abiotic diseases can cause significant problems for individual growers when favorable environmental conditions prevail. Brown spots form on flower, leaf, or stem tissue. One of the most commonly asked questions we get is, “How do you take care of poinsettias?” The secret to keeping poinsettia plants healthy and happy is knowing what continued care they need long after the holidays end. These popular Christmas plants contain a compound similar to that found in rubber latex -- and can cause … The star feature of poinsettias … Although there are a number of things that can go wrong from now until December 25, there … They are often disposed of once they start to fade, but with a little care, you can keep them all year and the bracts will colour up again the following year. Webbing may also be present with heavy mite populations. Pythium is usually most serious in early stages of poinsettia production when infected cuttings can wilt and die after transplanting. Apply a fungicide to protect plants. Do not combine the use of slow-release and soluble fertilizers. Grow at higher temperatures. Clean the greenhouse covering and space plants well. (Gray Mold)quickly colonizes damaged or senescing plant tissuesand initially appears as brown spots on the leaves and flower bracts. When poinsettias get problems, they always seem to hit hard and fast. Space plants to provide good air circulation. The base of infected stems appear soft and wet. In Hawai‘i, the disease tends It is a Gram-positive bacterium, very different from the Xanthomonas that causes angular leaf spots and the Dickeya and Pectobacterium species that cause cutting rots. We have described the major poinsettia diseases that are widespread in the industry. Poinsettias are very sensitive to cold temperatures and drafts. However, eating the plant is NOT recommended. Lack of molybdenum or acidic pH potting mixes (pH 4.5; 5.5 on some cultivars). Early in the season, cuttings wilt and yellow. Miscellaneous diseases and disorders; Bleaching necrosis: Air pollutant injury from either chlorides (> 0.5 ppm), nitrogen dioxide (> 2-3 ppm) or sulfur dioxide (> 0.5 ppm) : Bract necrosis: Physiological disorder favored by high humidity, heavy watering and high (ammoniacal) … Apply a fungicide to protect plants. A number of other less common biotic and abiotic diseases can cause significant problems for individual growers when favorable environmental conditions prevail. By watching for potential problems, understanding their causes andknowing the proper corrective actions to take, one can avoid most of theseissues. In soil. Why do we need this? Fungal Diseases of Poinsettias. Remove damaged tissues. Bract edge burn may cause serious problems in the final weeks of production or following boxing and transport. Several insects may attack poinsettias: white flies, fungus gnats, mealybugs and spider mites. poinsettiicola occurs rarely but was a serious problem for poinsettia production in 2010. Disease Symptoms Pathogen/Cause Management; Ammonium Toxicity: Root and top growth is restricted. Garden Retailers and Late Blight Disease. Xanthomonas campestris pv. Late in the season, roots turn black. Insecticides are not a good control option as they are not very effective. There are also many dwarf varieties available that grow to only 1–2m. Carefully inspect poinsettias and any other plants before you buy them or bring them into your home to avoid introducing pests or diseases. Root rot, over-fertilization, low light intensity, or lack of moisture. You must have JavaScript enabled in your browser to utilize the functionality of this website. When poinsettias get problems, they always seem to hit hard and fast. Several insects may attack poinsettias: white flies, fungus gnats, mealybugs and spider mites. The production time for an azalea crop, from propagation to flowering, could be as long as 3 years, so the price required to realize a profit is a handicap. Poinsettias (Euphorbia pulcherrima) are susceptible to a variety of issues when produced in a greenhouse.It is imperative for growers to monitor their crops carefully to avoid such problems. The fungus-like Pythium survives between crops in infected plant material from previous crops whether they are poinsettia or not. By far the most common problem with poinsettias is leaves shrivelling up and falling off. Poinsettias with Pythium root rot are often stunted, wilted despite media wetness, and slightly chlorotic. Fuchsia Rust. If it is below 50°F or windy outside then put your plant inside a loose-fitting bag. If you have a latex allergy, be careful around poinsettia plants. STORIES, MYTHS, LEGENDS AND THE FOLKLORE OF HELLEBORE. It can be troublesome in all stages of poinsettia production. Be careful when transporting poinsettias from the shop to your home in the winter, as the cold outdoor temperatures can damage the foliage. Molybdenum deficiencies can cause distorted leaves due to the failure of the interveinal areas to expand normally. There are also many dwarf varieties available that grow to only 1–2m. Further, leftover solution in the spray tank can cause trouble in the BCA areas when the tank is used again, and other chemistries are added that are not compatible. Large, light brown to tan, slightly sunken cankers form on older stems especially near large branches or crotches. Plants are stunted. Symptoms Rhizoctonia grows along the upper surface of the growing medium, so it often attacks the plant stem at the soil line. Whiteflies on poinsettias and other indoor plants are extremely difficult to control. Wounded stems of older plants develop soft rot and lodge. Poinsettias are extremely susceptible to root rot disease. Additionally, growers need to account for whitefly biotypes that have developed over the last decade or have the potential to develop insecticide resistance (i.e. ! Early season production diseases can include Xanthomonas leaf spot and Alternaria leaf spot. Don't put poinsettias in cold, drafty, or hot places. Apply a fungicide to protect plants. Symptoms . Apply a fungicide to protect plants at planting. Poinsettias can, at times, be a problematic crop, but beingaware of the more common nutritional, physiological and insect anddisease-related problems encountered during production can help reduce theheadaches. Disinfest tools. The pots of most poinsettias are set inside decorative pot covers. Disease causes the foul odor. Destroy infected plants. Under dry conditions, the pith of the lower stem is brown and the stem has a gray canker. Use only sterile soil and clean pots and tools. ... faced with a problem on Holy Night: she lacked the means to contribute a gift in the Christ Child ceremony at … Williams says different root rot pathogens cause trouble depending on where you currently are in the production cycle. Poinsettias are also susceptible to Rhizopus soft rot (Rhizopus stolonifera). With proper care, poinsettias can last longer than the traditional holiday season, and the information found in this section will help with that. The diseases listed in this table are not inclusive of all those that are known to occur on poinsettias. Keep hose ends off the ground. Yellowing is followed by burning of lower leaf margins. Longitudinal splits form at the stem base at and below soil line. Promptly remove fading flowers an… This fungal pathogen thrives under cool temperatures around 68-77°F. Apply a fungicide to protect plants as soon as any mildew is found. WHICH NATIVE ANIMALS EAT SLUGS AND SNAILS. If soluble salts become excessive, leach heavily, wait overnight, and leach again. See All Pest, Disease and Weed Identification, See All Beer, Hard Cider, and Distilled Spirits, See All Community Planning and Engagement. They need a minimum temperature of 13-15°C (55-59°F). Maintain low relative humidity in the crop canopy. It is often the cause of rot in cuttings, especially those under mist. Severely damaged plants should be discarded. Discard plants with symptoms. Several new … The holidays are here and the beautiful poinsettias are a very common flower for most house holds. Bract Edge Burn became a major problem in the late 1970s with the introduction of Gutbier V-14 Glory produced in southern climates. High substrate pH can induce nutrient problems in poinsettias. When the soil becomes dry to the touch, water the plant until water begins to flow out the bottom of the pot. Learn more about Poinsettia uses, effectiveness, possible side effects, interactions, dosage, user ratings and products that contain Poinsettia Xanthomonas campestris pv. Hey, it's the holiday season! disease. Everything you need to know about poinsettias: rich red bracts, deep green leaves and clusters of tiny, bright yellow or white flowers. Check the potting soil daily. Early season production diseases can include Xanthomonas leaf spot and Alternaria leaf spot. Plant wilt. Use sterile propagation media. The disease had probably gone unidentified for a number of years before plant pathologists were able to identify the pathogen. They are often thought to be poisonous but research shows that poinsettias contain no chemicals commonly considered toxic. In addition to biotic agents, improper fertilization practices can cause symptoms in poinsettias. Poinsettias with Pythium root rot are often stunted, wilted despite media wetness, and slightly chlorotic. In addition to biotic agents, improper fertilization practices can cause symptoms in poinsettias. Leaf margins yellow and burn. Scab caused by Sphaceloma poinsettiae, normally a disease problem only in states like Florida and Ha… The recommended pH range in a soilless substrate is 5.8 to 6.5. Conductivity readings at or above 1.0 mS for soil or 2.5 mS for soilless mixes (saturated paste extract) are excessive. Pythium root and stem rot is a common disease problem in poinsettias, and is often difficult to control. Avoid skin contact, as the sap can cause irritation in some people. For example, 5 percent of a spray solution with Orthene or Talstar insecticide residues can cause a lot of problems with BCAs when the tank is filled up to 100 percent and other, noncompatible product is added. Impatiens Necrotic Spot … The disease started on infected cuttings and continued through the entire production cycle. Each fungus can cause disease independently, or fungi may interact to produce rapid decline. When cooling your greenhouses as the poinsettias mature, avoid night temperatures below 60 F. Ventilate as much as possible during the day and water when foliage will be dry before night. Spray Options: Lewis Mites - Avid, Sirocco Spider Mites - Avid, Floramite, Sirocco Powdery mildew is most often a problem under cooler grower conditions. Longitudinal water-soaked streaks on stems and spots on leaves. * For additional information, see section on Key Diseases. Things like whitefly, Lewis mite, root rots, and nutritional issues can all quickly derail a quality crop. • Crud (physiological disorder): Dried drops of plant sap (latex) occurring in the bracts may interfere with normal bract development and cause disfigurement of the flower head. Several diseases affect production of poinsettia, ... Powdery mildew is a fairly recent disease problem in poinsettia production that can develop explosively late in the crop production cycle. Several diseases affect production of poinsettia, including foliar diseases such as Botrytis gray mold, powdery mildew, Alternaria blight, Xanthomonas blight, Erwinia blight, Phytophthora blight, and root diseases such as Pythium, Phytophthora and Rhizoctonia root rot. A number of other less common diseases can cause significant problems for individual growers when favorable environmental conditions prevail. Lower leaves yellow while leaf margins burn. As the top-selling potted plant in the United States, the poinsettia (Euphorbia pulcherrima) is historically rooted in the political world. Roots are rotted. Downy Mildews of Ornamental Plants. I have never known of poinsettias to give off any odor!! Cause and Disease Development Botrytis cinerea causes one of the most common diseases of all greenhouse crops. The first signs are generally a lack of good green leaf color, progressing to the classic bronzing symptoms that mites cause as they feed on the bottom side of the leaves. Favored by low light and low temperature in late fall, acidic potting mix, and exclusive use of ammonium nitrogen source. Use of molybdenum-containing fertilizer or a complete minor element supplement, or add sodium molybdate to soluble fertilizer. Hey, it's the holiday season! HOW TO COLLECT AND PREPARE TOMATO SEEDS FOR PROPAG... HOW TO COLLECT AND PREPARE PEAS FOR PROPAGATION. Stems often decay quickly, starting with the formation of brown to reddish brown lesions that enlarge, forming sunken cankers near the soil line … They run the biggest risk of succumbing to pests or disease while growing in the greenhouse at the nursery. High pH. The pathogen is restricted to poinsettia, however, and does not infect other plant species. The disease started on infected cuttings and … Apply a magnesium-containing fertilizer. A Poinsettia Problem Diagnostic Key is available online from North Carolina State University (68). Prevention is the best management strategy. Proximity to the plant itself can cause wheezing, rhinitis, asthma, and other symptoms in individuals with a latex allergy. Small, light-colored, round spots with yellow halos form on the leaf, particularly along the main vein. A major limiting factor in the production of a timely and healthy poinsettia … But it’s not just contact with the milky sap that can cause problems. Things like whitefly, Lewis mite, root rots, and nutritional issues can all quickly derail a quality crop. Williams says different root rot pathogens cause trouble depending on where you currently are in the production cycle. The disease had probably gone unidentified for a number of years before plant pathologists were able to identify the pathogen. Poinsettia used to be considered a poisonous plant. Keep hose ends off the ground. They can be stunning when they’re healthy, but a poinsettia with yellow leaves is both unhealthy and decidedly not festive. Young plants frequently are killed. Edema and Intumescence. Early in season, the rooted cuttings are stunted, yellow, and wilting. Downy Mildew of Impatiens. Iron deficiency is the most common problem … LEARN HOW TO STOP THE INVASIVE SPOTTED LANTERNFLY, Coronavirus: Information and resources for the Extension Community, Botrytis flower blight. Do not wet the foliage when irrigating. Houseplant Problems: Symptoms: Possible Causes: Control/Comments: Plant wilting: Overwatering or lack of water: overwatering can cause root rots. Poinsettia problems. If you are having difficulty diagnosing a specific disease(s) we encourage you to contact the Texas Plant Disease … Avoid overhead irrigation. Infected stems stretch several inches above the normal crop. ... conditions become favorable for bacterial growth (warm temperatures and high humidity), the bacteria multiply and cause disease. Phytophthora and Rhizoctonia can also rot the roots of poinsettias, and under favorable conditions, ... the cause of scab or spot anthracnose on both leaves and stems. Poinsettias: The problem children Heidi Wollaeger , Michigan State University Extension - October 24, 2013 Poinsettias are susceptible to diseases, distortion through rapidly changing environmental conditions, and uncommon nutrient deficiencies. Poinsettias: The problem children Heidi Wollaeger , Michigan State University Extension - October 24, 2013 Poinsettias are susceptible to diseases, distortion through rapidly changing environmental conditions, and uncommon nutrient deficiencies. Downy Mildew of Coleus. Largenumbers of gray to olivaceous green spores are produced on the infectedtissues. Poinsettias are a favorite Christmas plant but widely misunderstood. Sunken dark brown areas on stem may reach slightly above soil line. Symptoms vary with the pathogen. DISEASES Botrytis Optimizing the growing environment is still one of the best methods to limit Botrytis in your greenhouse. Poinsettias are extremely susceptible to root rot disease. Avoid purchasing insect-infested plants. Poinsettias are famous for their flower-like bracts that turn bright red in the winter time and earn them a place as an extremely popular Christmas plant. Telephone: (203) 974-8601 Fax: (203) 974-8502 Email: Sharon.Douglas@ct.gov. Get notified when we have news, courses, or events of interest to you. Lower leaves yellow and fall. Water should be able to drain from the bottom of containers. Molybdenum deficiency, Prepared by Gary W. Moorman, Professor of Plant Pathology. Poinsettia problems. High substrate pH can induce nutrient problems in poinsettias. Treat your poinsettia well throughout the holiday season. Poinsettias in growing mixes that do not contain mineral soil are unlikely to develop Thielaviopsis root rot. This disease thrives on dense-canopied plants such as poinsettias that hold a significant amount of moisture. Lower leaves yellow while leaf margins burn. Obtain virus‑free plants. Another culprit for problems on poinsettia is the fungal disease Botrytis, explains Mark Brotherton, portfolio leader at SePRO. problem in the commercial pro-duction of poinsettias, especially in greenhouses. Avoid root rots and over-fertilization. Cause: This is a very common greenhouse pest easily be transferred from the grower, to the retailer, and eventually to your home. High pH. The recommended pH range in a soilless substrate is 5.8 to 6.5. Avoid damaging established, well-branched plants. Mechanically transmitted. Cuttings wilt and die rapidly. Some other diseases can be problematic to poinsettias at any phase of production. poinsettiicola occurs rarely but was a serious problem for poinsettia production in 2010. In the garden, plants may grow to 4m tall and will need regular pruning to keep them within bounds. When purchasing plants, carefully check for whiteflies and other insects. Use of magnesium-containing limestone. Maintain even soil moisture levels. In some people, it can cause skin rash, eye irritation, and irritation or burns to the mouth. By entering your email, you consent to receive communications from Penn State Extension. Roots are brown and water soaked. Do not over-water or over-fertilize plants. Lime to adjust the soil pH above 5.5. For growing plants, beautiful gardens and propagation, How to Make a Natural and Organic Insecticide for Aphids. Favored by low light and low temperature in late fall, acidic potting mix, and exclusive use of ammonium nitrogen source. Herb Bedding Plants: Pest Management for Herb Bedding Plants Grown in the Greenhouse . Root and top growth is restricted. In the garden, plants may grow to 4m tall and will need regular pruning to keep them within bounds. ... soil becomes dry to the touch, water the plant until water begins to flow out the bottom of the pot. Poinsettias are very sensitive to cold temperatures and drafts. Our environmental conditions create a truly unique set of problems that must be overcome to produce a high quality product. The most important root disease affecting poinsettia is Pythium root rot caused by several species of Pythium the most common being P. aphanidermatum, but P. irregulare, P. cryptoirregulare and P. ultimum also cause loss. Botrytis may also cause stem blight (Figure 9) on cuttings and plants, often at branch crotches. Continue scouting throughout the season, especially as plants are being spaced. Use pasteurized soil and clean pots and tools. Warning Keep children and pets away from poinsettias because the sap can irritate skin and eating it may cause vomiting or other stomach problems. Plant Disease Management on Poinsettias The most serious disease problems of poinsettias are pythium root rot, rhizoctonia root and stem rot, botrytis, powdery mildew, fungal leaf spots, and bacterial issues. Fungicides do not make the white fungus go away after it is dead. This is why scouting might be more important in this crop than any other.. Here’s a month by month guide on what you should be looking for to prevent small problems from becoming big issues. Large roots and lower stem may be enlarged and ridged. Scout stock plants frequently and inspect cuttings as soon as they arrive. They're synonymous with Christmas, all around the world, and make fantastic festive decorations both inside and outside the home. In fact, bractsaccount for only 0.1 to0.5% of the total Ca2+ transported to the whole shoot and most of that is transported during the very early stages of growth. Diseases of Poinsettias. HOW TO COLLECT AND PREPARE FRENCH AND RUNNER BEAN... HOW TO COLLECT AND PREPARE LETTUCE SEEDS FOR PROPA... HOW TO COLLECT AND PREPARE MELON AND CUCUMBER SEE... HOW TO COLLECT AND PREPARE SWEET AND CHILLI PEPPER... HOW TO CHOOSE PLANTS FOR HOT, DRY BORDERS, THE HISTORY OF THE JACK 'O' LANTERN HALLOWEEN PUMPKIN, WHAT CAUSES POND WATER PROBLEMS AND HOW TO AVOID THEM, HOW TO MAINTAIN AND LOOK AFTER A HEALTHY POND. There are 5 surprising facts here, including the new myth about safety concerns. In nutrition experiments with the varieties Paul Mikkelsen, Annette Hegg and Eckespoint C-l an acid substrate increased the damage, owing to the relative insolubility (and thus unavailability) of Mo under these conditions. so even a slightly low Ca2+ contents may cause problems. Leaves yellow and fall. Don't put poinsettias in cold, drafty, or hot places. Source: Premier Tech How to Monitor Root Diseases All root rot diseases will ultimately result in … Caution. Poinsettias are cheery plants that are widely grown indoors over Christmas for their brightly coloured bracts. Fungus gnats are small, dark-colored flies about 3 mm (1/8 inch) long. Entering your postal code will help us provide news or event updates for your area. The adult white fly looks like a small fly covered with white powder. Destroy infected plants and crop debris. Figure 1: Root diseases commonly occur in poinsettias late in the season when it is easier to overwater due to colder temperatures, shorter day length and slow water uptake by the plant. Apply a fungicide to protect plants. Be nice to your plants! Poinsettias don’t usually have insect or disease problems once they make it to your home, particularly if you are just keeping them for the holiday season. Cuttings develop a soft rot at the base which moves upward quickly and kills the cutting. Over-watering will cause the lower leaves to turn yellow and drop. Botrytis. Box 1106 New Haven, CT 06504-1106. Do not use ammonium nitrogen sources exclusively. This is why scouting might be more important in this crop than any other.. Here’s a month by month guide on what you should be looking for to prevent small problems from becoming big issues. Whiteflies continue to be the major insect pest problem for poinsettias. The adults are more of a nuisance than a real problem, but the larvae do feed on plant tissue. 2001). Large, tan, sunken cankers may form onthe older stems, girdling the stem. Use a well-drained, soilless potting media labeled for houseplants. With a wide host range, Rhizoctonia can cause a variety of diseases including stem rot, root rot, damping-off in seedlings and aerial blight of leaves (Table 1). Diseases of Poinsettias. ... poinsettias can get fungal diseases and pests such as mealy bugs. Foliar Nematodes. Avoid skin contact, as the sap can cause irritation in some people. Roots are dark brown and the outer layers of root tissue strip off leaving a bare strand of inner vascular tissue exposed. Although there are other species known to cause plant disease, not all species of Rhizoctonia are plant pathogens. Treat your poinsettia well throughout the holiday season. View our privacy policy. Downy Mildew of Basil. Avoid damaging plants. Do not over-fertilize. The relative humidity within the plant canopy should be kept below 93percent throughout the production cycle. WHY IS MY POINSETTIA DROPPING ITS LEAVES? Over the last 10 years, it has become evident that BEB is cultivar-dependent. Immediately discard infected plants. If it is below 50°F or windy outside then put your plant inside a loose-fitting bag. ... What is the problem? Do not over-water during periods of low light and low temperature. Stem cankers cause defoliation and death of the distal plant parts. In continuous feed programs, 10% of the soluble fertilizer applied should leach out the bottom or clear tap water should be applied every second or third watering. Be nice to your plants! They do, however, represent those diseases that Texas growers experience most frequently. Discard infected cuttings and infested media. Yellow spots form on the upper surface of leaves. If these practices are followed, then fungicides can help in management. Disease problems caused by fungi and nematodes resulted in serious crop losses until better control measures were achieved. Pest pressure varies by region in greenhouse poinsettias, but the most common insects include whiteflies, mealybugs, mites and thrips. These plants produce colorful bracts and brighten rooms for the holidays, so it can cause concern when whiteflies infest a poinsettia. Use only sterile soil and clean tools, and hang up hose ends. Lower leaf margins are cupped downward. The water needs of a poinsettia can be determined with your finger. Poinsettias (Euphorbia pulcherrima), so familiar during the winter as houseplants, grow as perennials in U.S. Department of Agriculture plant hardiness zones 9 through 11. The disease causes a whitish, powdery discoloration of the upper and lowers surfaces of the leaves and colored bracts (Benson et al. The combined use of slow-release and soluble fertilizer or soluble fertilizer use with no leaching favors this. Poinsettias are susceptible to a wide variety of diseases that attack the Poinsettias need bright, but filtered light, away from strong sun and draughts. Favored by excess moisture and overcrowding of plants. Growers can reduce the potential of Botrytis by following a few crucial steps, Brotherton says. Apply a fungicide to protect plants. Molybdenum deficiencies can cause distorted leaves due to the failure of the interveinal areas to expand normally. Growing poinsettias in Texas is a challenge. White fungal growth in patches is seen on leaves and bracts. Powdery mildew is a fairly recent disease problem in poinsettia production that can develop explosively late in the crop production cycle. Over-watering will cause the lower leaves to turn yellow and drop. The star feature of poinsettias is the “flower” produced at the ends of branches. Healthy roots should be light-colored and firm. Defoliation and plant death follow. Informational table showing disease name, symptoms, pathogen/cause, and management of Poinsettia diseases. Poinsettias are subject to attack from insect pests and mites all season long, so effective management is a must for quality poinsettia production. Lower stems below ground may have a shredded appearance. And finally, a phytoplasma organism found associated with poinsettias provides evidence that some host/pathogen relationships can actually be economically beneficial. Control must prevent disease before bracts form. problems, as well as the cooler temperatures needed for finishing. We have described the major poinsettia diseases that are widespread in the industry. PP043 (3/01R) By Dr. Sharon M. Douglas Department of Plant Pathology and Ecology The Connecticut Agricultural Experiment Station 123 Huntington Street P. O. Diseases ofPoinsettias Stephen T. Nameth, OhioState University, DeptofPlant Pathology Successful poinsettia disease control/ management, or lack ofit, can mean the difference between a great crop andjoyous holiday season, and a terrible crop and "Bah, humbug." Leaf damage consisting of malformation, yellowing and necrosis, observed in poinsettias was found to be caused by Mo deficiency. Later in the season, plants defoliate and flower prematurely. Iron deficiency is the most common problem at substrate pHs above 6.5. Managing Pests and Disease.