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Bee Ling Poh, Amanda Gevens, Eric Simonne, and Crystal Snodgrass2 1. This document is HS1159, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date, August 2009. Visit the EDIS Web site at http://edis.ifas.ufl.edu. 2. Bee Ling Poh, graduate student, Horticultural Sciences Department; Amanda Gevens, assistant professor, Plant Pathology Department; Eric Simonne, associate professor, Horticultural Sciences Department, and extension director, Northeast Florida District; and Crystal Snodgrass, extension agent I, Manatee County, Palmetto, Fla., Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL. The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely. Read and follow directions on the manufacturer's label. Micronutrients such as boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) are essential for plant growth. Essential means that when micronutrient supply is insufficient, plants may develop deficiency symptoms and yields may be reduced. Because micronutrients are needed in relatively small quantities (a few pounds per acre compared to several tens or hundreds pounds per acre for macronutrients) and because excessive micronutrient applications may result in toxicity, all micronutrient applications should be taken into account when developing fertilizer programs for vegetable crops. The University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) recommendations for micronutrient application are based on the results of pre-season soil tests (Table 1). In addition, plant nutritional status in micronutrients may be determined during the growing season with leaf analysis (Simonne and Hochmuth 2009, Hochmuth et al., 2004). When soil test or tissue analysis indicate that micronutrients are needed, sources that are commonly used include boric acid for B, copper sulfate or copper chloride for Cu, iron sulfate or chelates for Fe, manganese sulfate or manganese chloride for Mn, molybdic acid or molybdenum oxide for Mo, and zinc sulfate or zinc chloride for Zn. However, because micronutrients such as Cu, Mn and Zn are also present in several fungicides, vegetable growers may wonder whether they still need to apply Cu, Mn or Zn when these fungicides are used. Using tomato as an example, this document lists the common sources of micronutrients in common fungicides, estimates micronutrient applications for an entire crop, and discusses the availability of these micronutrients. This document does not encourage the use of fungicides for the purpose of micronutrient applications to crops, but indicates that contributions
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 2 of micronutrients from fungicides should not be ignored. The amount of metal in the fungicide is stated in fungicide labels, often expressed as percent metallic equivalent for copper and sometimes as elemental copper. For manganese and zinc, the percent metallic equivalent is used in maneb and ziram, respectively. However, in mancozeb, the amounts are expressed as percentages of Mn++ and Zn++. When the label states that the product contains 50% metallic copper equivalent, it means that there are 50 lbs Cu/100 lbs fungicide. Similarly, a fungicide with 16% Mn++ means that 100 lbs of the fungicide contain 16 lbs of Mn++. Many copper fungicides such as Kocide and Champ are formulated using copper hydroxide as the active ingredient and may contain as much as 50% metallic copper equivalent. Manganese-containing fungicides with the active ingredient maneb include Maneb 80WP and contain 16.5% Mn equivalent. The most common Mn-containing fungicides are those made with mancozeb as the active ingredient. These fungicides, such as. Dithane or Manzate, may contain up to 16% Mn++ and 2% Zn++. Newer products available for commercial use may contain all three elements. For example, ManKocide 61.1 DF contains 30% Cu, 3% Mn and 0.4% Zn. Metal-based fungicides are usually protectant fungicides that need to be applied onto plant surfaces prior to pathogen infection in order to reduce the incidence of the infection. In a standard preventive fungicide program, metal-based products could be applied several times during a growing season, typically at application intervals of 7-10 days. Depending on the types of fungicides used, plant micronutrient needs may be met through fungicide applications (Table 2). For example, in a tomato crop, as much as 12 lbs per acre of Cu are applied per season through the use of Kocide 101, which far exceeds the UF/IFAS recommended micronutrient application rate of 1.25 lbs Cu per acre. However, if liquid copper is used, it may be necessary to supplement with foliar fertilizer to correct any Cu deficiency noted in testing. When Bonide Liquid Copper is used (and it often is used for home vegetable gardens), the maximum amount of Cu added per season is only 1.8 lbs per acre. Similarly, high amounts of Mn are supplied through fungicide applications if maneb (Maneb 80WP) or mancozeb (Dithane M45) are used at the maximum rates during the season. However, Zn contribution from mancozeb-based fungicide applications is low as the Zn content of such fungicides is low. By contrast, substantial amounts of Zn are applied through the use of high-Zn fungicides such as Ziram 76DF (16.3% Zn). The discussion above focused on calculating the total quantities of Cu, Mn or Zn applied under several disease-control programs. However, a basic principle of plant nutrition is that the presence of a nutrient does not equate with plant-availability. This principle applies regardless of whether the nutrient is derived from fertilizer or fungicide. Soil pH is a major factor affecting nutrient availability. A high soil pH can immobilize micronutrients, which become unavailable to plants. Current UF/IFAS standardized recommendations call for maintaining soil pH between 6.0 to 6.5, but most sandy soils in South Florida have pH as high as 8.0 due to accidental over-liming or use of alkaline irrigation water (Simonne and Hochmuth 2009). In such a case, it would be necessary to provide periodic applications of micronutrients to correct any deficiency. In regards to plant availability of micronutrients from fungicidal sources, two other factors need to be considered, as well -uptake interference between micronutrients and type of formulations.
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 3 The application of copper fungicides has been found to interfere with the uptake of other micronutrients, such as Zn (Sonmez et al 2007). If fungicides were applied as tank-mixes, eg. Cu fungicide mixed with Mn/Zn fungicide, Cu uptake may suppress Mn and Zn uptake by the plants. It would be necessary to monitor the plants for signs of Mn or Zn deficiency after such a mixed application. Additionally, while absorption of Cu and Mn from fungicides is well documented (Sonmez et al 2007, Kaplan 1999, Deckers et al 1997, Shu et al 1992, Mollenhauer and Smith 1954, Emge and Linn 1952), reports documenting Zn absorption from fungicides are mixed. It has been determined that Zn in certain formulations such as ziram (zinc dimethyldithiocarbamate) is not as readily absorbed (Mollenhauer and Smith 1954) compared to Zn from zineb (zinc ethylene bis-dithiocarbamate) (Pire 1987, Emge and Linn 1952). Care should be taken when interpreting micronutrient contributions from Zn fungicides, and a plant tissue test should be used to check for Zn sufficiency after the fungicidal spray. Similarly, for new formulations of Cu and Mn, it should not be taken for granted that they will contribute micronutrients as the nutrient may be in a form that is not absorbable by the plant. For fungicides of other crops, read the label to find out how much % metallic equivalent of the micronutrient is present in the fungicide and the recommended amount in lb per acre of fungicide to be applied. Multiply the % metallic equivalent to the lb per acre of fungicide to determine the total contribution of nutrient from the fungicide. Take note of possible factors that would affect the availability of nutrients from the fungicides -such as soil pH, interferences from using tank mixes and type of formulations. Do not assume that once the fungicide is applied, micronutrients in the fungicide will be available to the plants. If not sure, monitor closely after the fungicidal spray, and do a plant-tissue test for the micronutrient if necessary. Micronutrients Cu, Mn and Zn are supplied through metal-based fungicide applications, but only Cu and Mn are applied in sufficient quantities to meet crop needs, depending on the type of fungicide, amount of nutrient in the fungicide and the maximum rate applied per crop season. Careful calculations of the amount of micronutrients from fungicides and consideration of possible factors affecting availability are needed to reach a meaningful decision regarding whether additional micronutrient fertilizers should be applied. Rather than relying solely on the information provided here, growers should use the label of new products or formulations to determine the amount of micronutrients supplied by their fungicide program. Deckers, T., E. Daemen, K. Lemmens and C. Missotten. 1997. Influence of Foliar Applications of Mn During Summer on the Fruit Quality of Jonagold. Acta Horticulturae 448: 467-474. Emge, R. G. and M. B. Linn. 1952. Effect of Spraying with Zineb on the Growth and Content of the Tomato Plant. Phytopathology 42: 133-136. Hochmuth, G., D. Maynard, C. Vavrina, E. Hanlon and E. Simonne. 2004. Plant Tissue Analysis and Interpretation for Vegetable Crops in Florida. http://edis.ifas.ufl.edu/EP081, EDIS Publication HS964. Department of Horticultural Sciences, Fla Coop. Ext Ser. IFAS, Univ. of Fla., Gainesville, FL. Mollenhauer, R. and C. B. Smith. 1954. Tomato Plant Absorption and Translocation of Manganese and Zinc from Dithiocarbamate Fungicide Sprays. Proceedings of the American Society for Horticultural Science 63:297-303. Kaplan M. 1999. Accumulation of Copper in Soils and Leaves of Tomato Plants in Greenhouses in Turkey. Journal of Plant Nutrition 22:237-244. Olson, S.M., W.M. Stall, G.E. Vallad, S.E. Webb, T.G. Taylor, S.A. Smith, and E.H. Simonne. 2009. Tomato Production in Florida, pp. 291-312. In:
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 4 S.M. Olson and E. Simonne (Eds.) Vegetable Production Handbook for Florida, Vance Publishing, Lenexa, KS. Pire, R. 1987. Correction of Zinc Deficiency in Grapevine by Treating Pruning Wounds. Acta Horticulturae 199:157-161. Shu, Z. H., T. F. Sheen, S. L. Lin and K. C. Lee. 1992. Effects of Microelement-containing Pesticides on Nutrient Concentration of Mango Leaves. Acta Horticulturae 321:553-560. Simonne, E. H. and G. J. Hochmuth. 2009. Soil and Fertilizer Management for Vegetable Production in Florida, pp.3-16. In: S.M. Olson and E. Simonne (Eds.) Vegetable Production Handbook for Florida, Vance Publishing, Lenexa, KS. Sonmez, S., M. Kaplan, N.K. Sonmez, H. Kay and I. Uz. 2007. Effect of Soil Copper and Foliar Copper Applications on Micronutrient Contents of Tomato Plants. Asian Journal of Chemistry 19(5):3929-3940.
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 5 UF/IFAS Recommendations for Foliar Applications of Micronutrients to Vegetable Cropsz,y (lb product per acre) (%) (lb per acre) Boron Borax Solubor 2 5 1 1.5 11 21 0.55 0.32 Copper Copper sulfate 2 5 25 1.25 Iron Ferrous sulfate Chelated iron 2 3 0.75 1 20 5 12 0.60 0.12 Manganese Manganous sulfate 2 4 28 1.12 Molybdenum Sodium molybdate 0.25 0.50 39 0.20 Zinc Zinc sulfate Chelated zinc 2 4 0.75 1 36 6 14 1.44 0.14
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 6 List of Fungicides Containing Copper, Manganese or Zinc and Commonly Used in Tomato Production in Florida (per acre) (%) Per Applic Per Seasonv Per Applic Per Season Per Applic Per Season Kocide 101 or Champion 77 WPs Copper hydroxide 4 lbs NS 50 2.0 12.0 + Kocide 4.5 LF Copper hydroxide 2.66 pts NS 24.4 (or 3 lb/A) 1.0 6.0 + Kocide 2000 53.8 DF Copper hydroxide 3 lbs NS 35 1.1 6.6 + Champ 57.6 DP Copper hydroxide 1.3 lbs NS 37.5 0.5 3.0 + Basicop 53 WP Tribasic copper sulfate monohydrate 4 lbs 53 2.1 12.6 + Kocide 61.4 DF Copper hydroxide 4 lbs NS 40 1.6 9.6 + Nu Cop 50 WP Copper hydroxide 4 lbs NS 50 2.0 12.0 + Cuprofix Disperss Ultra 40 DF Basic copper sulfate 3 lbs NS 40 1.2 7.2 + Bonide Liquid Copperu Copper octanoate 2 gals NS 1.8 0.3 1.8 Ridomil Gold Copper 64.8 W Copper hydroxide, mefenoxam 2 lbs NS 39.1 0.8 4.8 + Mankocide 61.1 DF Mancozeb, copper hydroxide 5 lbs 112 lbs 30 3 0.4 1.5 33.6 + 0.15 3.36 + 0.02 0.45
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 7 List of Fungicides Containing Copper, Manganese or Zinc and Commonly Used in Tomato Production in Florida (per acre) (%) Per Applic Per Seasonv Per Applic Per Season Per Applic Per Season Manex 4F Maneb 2.4 qts (0.6 gal) 16.8 qts (4.2 gal) 7.6 (or 4 lb/gal AI) 0.49 3.45 + Maneb 75DF Maneb 3 lbs 22.4 lbs 16.5 0.50 3.70 + Maneb 80WP Maneb 3 lbs 21 lbs 16.5 0.50 3.47 + Dithane, Manzate, Penncozeb 75DF Mancozeb 3 lbs 22.4 lbs 15 1.9 0.45 3.36 + 0.06 0.43 Dithane F45, Manex II 4FL Mancozeb 2.4 qts (0.6 gal) 16.8 qts (4.2 gal) 7.4 (or 4 lb/gal AI) 0.9 0.48 3.36 + 0.06 0.47 Dithane M45, Penncozeb 80WP, Manzate 80WP Mancozeb 3 lbs 21 lbs 16 2.0 0.48 3.36 + 0.06 0.42 Ridomil MZ 68 WP Mancozeb, mefenoxam 2.5 lbs 7.5 lbs 12.8 1.6 0.32 0.96 0.04 0.12 Gavel 75DF Mancozeb, zoxamide 2 lbs 16 lbs 13.3 1.7 0.27 2.13 + 0.03 0.27 Ziram 76DF Ziram 4 lbs 24 lbs 16.3 0.65 3.90
Estimating Copper, Manganese and Zinc Micronutrients in Fungicide Applications 8 List of Fungicides Containing Copper, Manganese or Zinc and Commonly Used in Tomato Production in Florida (per acre) (%) Per Applic Per Seasonv Per Applic Per Season Per Applic Per Season z Mention of trade names is solely for the purpose of providing specific information and does not imply a recommendation over similar products. Always read and follow the instructions on the product labels. y See Olson et al., 2009 for complete disease-management recommendations for tomato grown in StateplaceFlorida x NS= None Specified on the label w Specimen labels of fungicides are obtained from Crop Data Management Systems, Inc. (http://www.cdms.net/LabelsMsds/LMDefault.aspxn) except for those stated below: Kocide 101, http://msds.dupont.com/msds/pdfs/EN/PEN_09004a358023d1e0.pdf nKocide 4.5 LF, http://msds.dupont.com/msds/pdfs/EN/PEN_09004a358023c96d.pdf Bonide liquid copper, http://www.bonideproducts.com/retail_support/new_images/index.php Manzate 75DF, http://www.hort.wisc.edu/cran/mgt_articles/articles_pest_mgt/labels_msds/labels/manzate%2075DF.pdf nManzate 80WP, http://aesop.rutgers.edu/~plantbiopath/links/bbcpestweb/CranberryLabels/manzate80.pdf nManex II 4FL, http://www.hort.wisc.edu/cran/mgt_articles/articles_pest_mgt/labels_msds/labels/Manex%20II.pdf vAssuming six applications in one season (unless otherwise stated) based on a 70-day growing period with fungicide sprays applied at 10-day intervals u Bonide liquid copper is commonly used for home vegetable growing. The label does not indicate maximum rate of product to use per acre, and the rate used here is based on its parent product, Cueva fungicide. The label states a 1.8% metallic copper equivalent, which is assumed to be 1.8% w/v. t +indicates the amounts provided by fungicides when used at maximum rates for the season are equal to or greater than those of the recommended fertilizer rate; - indicates lower amounts from fungicides than the recommended fertilizer rate.