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Down the Garden Path: On the lookout for pests? Up your game with growing degree days · Kendall County News - Shaw Local

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  Speaker 1: Down the garden path on the lookout for pests. Up
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  Speaker 1: your game with growing degree Days. Written by Susan Summers
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  Speaker 1: and University of Illinois Extension. This article is being read
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  Speaker 1: by an automated voice brought to you by ever Lit.
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  Speaker 1: It's that time of year. The weather is warming, plants
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  Speaker 1: are greening up, and many of us are in the garden.
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  Speaker 1: The warmer temperatures also bring the return of insect and
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  Speaker 1: disease pests. How can we keep one step ahead of
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  Speaker 1: these unwonted visitors. A tool that can help is growing
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  Speaker 1: degree days or GDD for short. So let's get acquainted
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  Speaker 1: with GDD. To do this, we will work through a
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  Speaker 1: bit of math and then I will show you how
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  Speaker 1: to use GDD without the math CONSTANCEPT and math behind GDD.
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  Speaker 1: GDD is a metric for the accumulated heat experienced by
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  Speaker 1: pest organisms starting at a specified date, often March first.
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  Speaker 1: The idea is that garden pests develop slowly at cool
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  Speaker 1: temperature and more rapidly at warm temperatures. The simplest way
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  Speaker 1: to calculate GDD is by using a temperature averaging formula.
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  Speaker 1: For each day. The base temperature is typically fifty degrees fahrenheit.
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  Speaker 1: If the formula result is negative, then the contribution for
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  Speaker 1: the day is zero. This contribution is added to a
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  Speaker 1: running total from prior days. The result is the cumulative
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  Speaker 1: GDD on that day. The table provides example results from
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  Speaker 1: this method. As the season progresses and temperatures climb, GDD increases.
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  Speaker 1: This is shown by the plot of GDD for three
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  Speaker 1: consecutive growing seasons. Notice that GDD differs from year to year,
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  Speaker 1: increasing to larger values in years having more warm days.
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  Speaker 1: The plot indicates that twenty twenty four was warmer than
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  Speaker 1: the other years. This is important because pests appear earlier
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  Speaker 1: in warmer years. Practical use of GDD. To use GDD
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  Speaker 1: to manage garden pests, First, keep track of the GDD
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  Speaker 1: for your area. You can perform the calculations described above,
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  Speaker 1: or you can check out the reas sources below. Second,
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  Speaker 1: know the GDD for a given pest's appearance. Here are
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  Speaker 1: three examples adult Japanese beetles chew leaves at a GDD
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  Speaker 1: between nine hundred and twelve hundred last year that happened
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  Speaker 1: in late June. Magnolia scale feeds on the sap of
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  Speaker 1: magnolia trees, creating a sticky mess beneath the canopy. The
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  Speaker 1: crawler stage is most readily managed. It begins at a
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  Speaker 1: GDD of nineteen fifty last year that happened in late July.
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  Speaker 1: Squash vine borer is a pest of summer squash. Adult
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  Speaker 1: moths emerge from the soil near where plants were impacted
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  Speaker 1: last year. These moths lay eggs at a GDD between
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  Speaker 1: nine hundred and one thousand. The eggs hatch into larvae
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  Speaker 1: that bore into stems to feed, causing plant wilting and death.
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  Speaker 1: When will these pests appear in twenty twenty six? Rather
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  Speaker 1: than guests, stay up to date on the twenty twenty
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  Speaker 1: six GDD values and know onen to be on the
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  Speaker 1: lookout and assess control strategies. To use GDD in your garden,
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  Speaker 1: check out the Plant Healthcare Report published by the More
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  Speaker 1: and Arboretum. This weekly report provides GDD pest activity, pest identification,
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  Speaker 1: and management options. For pest specific GDD values, Visit this
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  Speaker 1: University of Wisconsin Extension web page. Try the GDD models
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  Speaker 1: from Oregon State University. Susan Summers is a certified Master
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  Speaker 1: Gardner volunteer with University of Illinois extensions serving DuPage, Kane,
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  Speaker 1: and Kendall counties.