U of M ENT 4015 - Degree-Day and Phenological Models

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Degree-Day & Phenological ModelsRoad map for today’s talkWhat are degree-days?Slide 4ExamplesExamplesSlide 7Calculating degree-daysSlide 9Slide 10Using degree-days to predict insect and plant developmentSlide 12Slide 13Using plant phenology to predict insect activitySlide 15Slide 16Slide 17Krischik, V and J. Davidson. 2004. IPM of Midwest Landscapes. University of Minnesota Experiment Station, 335pp. $451. Examples2. Examples3. Examples4. Examples5. Examples6. Examples7. Examples8. Examples9. Examples10. ExamplesTo tape or not to tape: Degree-days, confirming model predictions, and microhabitatsUsing degree-days to predict insect developmentSan Jose Scale recommendations from Arkansas, California, Illinois, Indiana, Kentucky, Minnesota, New York, Vermont, VirginiaDegree day models for California red scaleDamage: California red scale attacks twigs, leaves, branches, and fruit by sucking on the plant tissue with their long, filamentous mouthparts.Damage: Severe infestations cause leaf yellowing and drop, dieback of twigs and limbs, and occasionally death of the tree.Life history: California red scale can be found on the wood as well as on fruit and leaves.Life history: Crawlers move around to find a suitable place to settle and can be spread about by wind, birds, or picking crews.Life history: With each molt the female cover develops a concentric ring center.Life history: Males form elongated covers while the female covers remains circular.Biological control: Comperiella bifasciataBiological control: Aphytis melinusBiological control: Aphytis sp.Biological control: AphytisBiological controlBiological control: Rhyzobius lophanthaeBiological control: Chilocorus orbusBiological control: Chilocorus orbusPowerPoint PresentationSlide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Dr. Vera KrischikDept. Entomology, University of MinnesotaDegree-Day & Phenological Degree-Day & Phenological ModelsModels1. Degree-day DD models give an idea when an insect emerges; best time to use pesticides.2. Need good scouting from multiple sources.3. Phenological models easier, less infrastructure to use.4. Microhabitat: use tape to monitor for crawlers.Road map for today’s talkRoad map for today’s talkTo effectively control pest populations, pest managers need to be familiar with:*The host plant; its life cycle, vulnerable stage of development, cultural needs, symptoms of stress and common pest problems.*Pests; their life cycle, vulnerable stages of development, cultural needs, and natural enemies.*Economic threshold of damage.What are degree-days?What are degree-days?A degree-day is a measure of the amount of heat that accumulates above a specified base temperature during a 24-hour period. The lower temperature threshold for development is used as the base temperature for calculating degree-days. Experience has shown that 50°F is a reasonable base temperature for many species. Although other temperatures such as 32° and 42°F are also sometimes used. What are degree-days?What are degree-days?D. A. Orton & T. L. Green. 1989. COINCIDE, The Orton D. A. Orton & T. L. Green. 1989. COINCIDE, The Orton System of Pest Management. Plantsmen's PublicationsSystem of Pest Management. Plantsmen's PublicationsPest Life Stage DD50 Silver maple, Acer saccharinum Serviceberry, Amelanchier laevis European pine shoot moth Larvae 50-100 Floral buds Spruce gall adelgid Adult Female 50-100 First leaves Floral buds ExamplesExamplesD. A. Orton & T. L. Green. 1989. COINCIDE, The Orton D. A. Orton & T. L. Green. 1989. COINCIDE, The Orton System of Pest Management. Plantsmen's PublicationsSystem of Pest Management. Plantsmen's PublicationsPest Life Stage DD50 Silver maple, Acer saccharinum Serviceberry, Amelanchier laevis Cankerworms Larvae 100-200 Bloom European pine sawfly Larvae 100-200 Bloom Spruce budworm Larvae 100-200 Bloom Eastern tent caterpillar Lavae 100-200 Leaf 1-2 Bloom ExamplesExamplesD. A. Orton & T. L. Green. 1989. COINCIDE, The Orton D. A. Orton & T. L. Green. 1989. COINCIDE, The Orton System of Pest Management. Plantsmen's PublicationsSystem of Pest Management. Plantsmen's PublicationsPest Life Stage DD50 Silver maple, Acer saccharinum Serviceberry, Amelan chierlaevis Birch leafminer 275-500 Seeds Lilac borer Larvae 275-500 Seed ripe Bronze birch borer Larvae 400-600 Elm leaf beetle Larvae 400-600 Bagworm Larvae 700-800 Fruit ripe ExamplesExamplesThere are a number of ways to calculate degree-days, ranging from quite simple to those so complex that a computer is required. All three methods calculate degree-days from the daily minimum and maximum temperature, and a specified base temperature. 1. Average Method 2. Modified Average Method3. Modified Sine Wave Method Calculating degree-daysCalculating degree-daysDuring a typical 24-hour day, the minimum temperature is usually reached just before dawn and the maximum temperature during mid-afternoon. Daily temperature data can be obtained from a thermometer that records maximum and minimum temperatures, or from a nearby weather station. Calculating degree-daysCalculating degree-daysDegree-days = [(max temp + min temp) / 2] – base tempUsing this method, 5 degree-days accumulated during the day when temperatures ranged from 45 to 65[(65 + 45) / 2] – 50 = 5 degree-daysIf the maximum temperature for the day never rises above the base temperature, then no development occurs, and zero degree-days accumulate. Calculating degree-daysCalculating degree-daysCumulative degree-days = total number of degree-days that have accumulated since a designated starting date, and they are calculated simply by adding the number of degree-days that accumulate each day. Any date can be used as the starting-date, but January 1 is used most commonly because many overwintering plants and insects do not resume development until they are first exposed to a period of cold.Using degree-days to predict insect Using degree-days to predict insect and plant developmentand plant developmentConstruct a degree-day model by monitoring a phenological event from one year to the and by noting the total number of degree-days that have accumulated. For example, monitor adult emergence of bronze birch borer and flowering of crabapple. Record the cumulative degree-days or the total number of degree-days that have


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