Hemileia Vastatrix) in Hawaiʻi Andrea M
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Plant Disease June 2021 PD-118 Spraying to Suppress Coffee Leaf Rust (Hemileia vastatrix) in Hawaiʻi Andrea M. Kawabata1 and Stuart T. Nakamoto2 1Department of Tropical Plant and Soil Sciences 2Department of Human Nutrition, Food, and Animal Sciences Coffee Leaf Rust (CLR), Hemileia Plant susceptibility to CLR attack vastatrix, has been identified in Hawaiʻi. increases with berry yield and host This disease of coffee will cause defolia- density [4]. Field sanitation, proper tion, reduced berry size, branch, and tree pruning, fertility, CLR monitoring, death. Infections typically start on the and early detection are key for re- lower portion of the tree before reaching ducing this pathogen threat to tree the higher leaves. The first symptoms are health and production. When applied small, pale yellow spots on the upper properly, and at <5% infection rate of surface of leaves (Fig. 1A). On the under- total farm foliage, contact fungicides sides of leaves, infectious spores appear can be helpful in protecting coffee resembling a patch of yellow- to dark trees from initial and increased dis- orange-colored powder (Fig. 1B, Fig. 2). ease severity [10]. Physical removal, These young lesions steadily increase in containment, and destruction of leaves size, with the center of the lesion turning and branches displaying lesions can necrotic and brown [1]. Stem and berry help to reduce CLR inoculum and infection are rare, but CLR can also af- infection [2]. fect young seedlings. Only contact fungicides have been available for Hawaiʻi coffee producers; Why spray to suppress coffee however, on May 19, 2021, Priaxor® Xe- leaf rust? mium® Brand Fungicide, a translami- Over a three- to five-month period, nar (localized systemic) fungicide, was one CLR lesion can produce upwards approved for use on coffee in Hawaiʻi of 400,000 spores that become airborne under an Environmental Protection and easily spread throughout a farm and Agency Section 18 Emergency Exemp- between farms. If left untreated, berry tion. Information about this product is production and foliage losses caused not included in this publication. Contact by CLR on non-resistant coffee variet- your statewide coffee agent to learn ies can be significant, ranging between Figure 1: Coffee leaf rust on the about Priaxor Xemium and its Section 30% and 80% [4,5]. Yield is completely upper leaf surface (top) and lower 18 use requirements and directions. See lost when the tree is killed. leaf surface (bottom) of coffee. page 4 for contact details. Brackets e.g. [2], correspond to literature citations found in the Literature Cited section. This publication is expected to evolve as more is learned about coffee leaf rust in Hawai‘i. Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in co- operation with the U.S. Department of Agriculture, under the Director/Dean, Cooperative Extension Service/CTAHR, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i 96822. Copyright 2018, University of Hawai‘i. For reproduction and use permission, contact the CTAHR Office of Communication Services, [email protected], 808-956-7036. The university is an equal opportunity/affirmative action institution providing programs and services to the people of Hawai‘i without regard to race, sex, gender identity and expression, age, religion, color, national origin, ancestry, disability, marital status, arrest and court record, sexual orientation, or status as a covered veteran. Find CTAHR publications at www.ctahr.hawaii.edu/freepubs. UH–CTAHRUH-CTAHR Spraying to Suppress Coffee Leaf RustTitle (Hemileia vastatrix) in Hawaiʻi PD-118 —Junenumber 2021 — date Suggestions for Preventative and Suppres- sion Spray Applications THE LABEL IS THE LAW. READ AND FOLLOW PRODUCT LABELS FOR ALL PESTICIDES. PRODUCT ROTATION IS HIGHLY RECOMMENDED TO REDUCE THE RISK OF PESTICIDE RESISTANCE BY COFFEE LEAF RUST AND OTHER DISEASES. Personal protective equipment (PPE): • Follow the label for proper use of PPEs. o Disposable PPEs may be a consideration for use. Type of sprayer: • According to experts at CIRAD, a French agricultural research center, motorized sprayers should not be used for initial CLR treatments to contain spores [3]. o Spores may become airborne and spread if using a high-pressure sprayer. o Reduce sprayer pressure or change the nozzle to Figure 2: Close-up of powder-like coffee leaf rust spores create larger droplets as needed. on the underside of a coffee leaf. • Water quantity per acre will depend on individual spray calibration for your trees and farm. No other systemic fungicides are currently available o Calibrate your sprayer by following the examples for Hawaiʻi producers to use on coffee for CLR control. and directions in publications for sprayer calibration This document provides suggestions for producers on [7-9]. the use of fungicides for both the suppression of CLR on farms and to reduce establishment severity of the patho- Where and what to spray: gen. Special attention is needed for pesticide resistance • Spray the entire coffee tree, with emphasis on the un- management to fungicides with product rotation and dersides and topsides of the leaves. proper use. Additional CLR information can be found o A CLR spore produces a germ tube (germinates) at www.HawaiiCoffeeEd.com/clr. that enters the plant via the stomata, which are Table 1 provides a list of fungicides approved by the found on the undersides of leaves [5]. Hawaiʻi Department of Agriculture for use on coffee • Spray all producing, non-producing, and seedling cof- in Hawaiʻi, and lists CLR on the label. Although there fee plants. are other fungicides approved for use in Hawaiʻi, unless o Good spray coverage is important. coffee is listed on the label, you should not use these o A slowed walking pace and deliberate spray ap- products on your coffee crop. Failure to adhere to pesti- plication may be necessary to achieve complete cide regulations could result in legal action and fines by coverage of the tree foliage and leaf surfaces. regulatory authorities. • Consult the label about intentional ground spraying. o Field sanitation and early detection of CLR is 2 UH–CTAHRUH-CTAHR Spraying to Suppress Coffee Leaf RustTitle (Hemileia vastatrix) in Hawaiʻi PD-118 —Junenumber 2021 — date important. o If anticipating rain, a sticker and spreader could o CLR mycelium require a living host tissue or cell improve spray adhesion and coverage. to remain alive; however, its urediniospores can • Foliar fertilizers survive about six weeks and through dry periods o Consult with the fungicide and foliar fertilizer [1]. labels. • Reduce the development of pesticide resistance to the • Approved Beauveria bassiana products products listed in Table 1. o Review the product label and the BioWorks Botani- o It will be more difficult to control diseases with Gard® compatibility chart. resistance to approved fungicides. o https://www.bioworksinc.com/wp-content/uploads/ o Alternate and rotate the use of fungicides in dif- products/shared/botanigard-tank-mix-compatibil- ferent FRAC groups, as listed in Table 1. ity.pdf • This typically applies to the use of all pesticides, o According to the above link, tests were not car- unless noted on the label. ried out to evaluate impact on the partner product o For example, if you use a blue product like Serenade integrity or for plant phytotoxicity. ASO (FRAC Group 44) for your first application, then use a yellow product, such as Kocide 3000 Spraying to control anthracnose (Colletotrichum sp.) (FRAC Group M1), for your next application. and cercospora leaf spot and berry blotch (Cercospora Then, switch back to Serenade or rotate to a pink coffeicola) [5] on coffee, as well as CLR: product (FRAC Group BM 02). Avoid using the • Spraying to control Colletotrichum sp., another fungal same-colored product in back-to-back applications. disease on coffee in Hawaiʻi, may require higher rates o If your farm is certified organic, an example for than necessary for CLR. Consult the product label. rotation is to use a pink product like DoubleNickel • Conduct annual or biennial leaf tissue and soil sample LC, then use a yellow product like Badge X2 next. tests to determine and prevent plant and soil toxicities Then, switch back to DoubleNickel LC or rotate to when applying copper-based and other products. a blue product. Again, avoid using the same-colored product in back-to-back applications. Other important considerations: • Maintain proper record keeping of pesticide use. When to spray: • Re-entry interval (REI) following a spray application. • Avoid spraying during rain, drought, or high heat, if o Follow the required REI, being especially mindful possible. of pickers and when they will enter the field for • Follow the product label for frequency of application. harvest. o Also, follow any restrictions regarding application Other additions to the fungicide: before crop harvest. This is typically referred to • Consult with the product label before mixing and com- on the label as the Pre-Harvest Interval, or PHI. bining other products with the fungicide. • pH of spray solution. o Some pesticide products are not compatible with o Labels may have warnings for phytotoxicity with certain additives, such as those noted below. low (or high) pH of the spray solution. o If the mixture of products causes phytotoxicity on • Minimum and maximum rates per application. the coffee trees, stop applications immediately. o Follow the label rate. Underuse of a product can • Sticker/spreader cause pesticide resistance by the pest or disease o Stickers help the product to adhere to the surface and additional losses if spray applications are inef- and remain on the plant following application fective. o Spreaders and adjuvants help with dispersal and o Overuse of a product can cause plant, soil, and coverage by reducing water surface tension and environmental toxicities and hazards, is a viola- allowing the droplets to spread and cover more tion of product use, and has increased costs to the surface area on leaves, branches, berries, etc.