What in the Weather?

This Day in Iowa Weather History: 1970 early season snowstorm brought 5.1 inches to Sioux City - their earliest 1+ inch accumulation on record Current Weather Forecast: Slight warm-up through the weekend with above-average temperatures Isolated chance of showers/thunderstorms overnight and late Saturday into Sunday No widespread frost expected through at least October 24th Climate Outlook: 8-14 day outlook: leaning warmer and slightly wetter October outlook: warmer with equal chances for precipitation La Niña Advisory issued - conditions present and expected to persist through December 2025-February 2026 La Niña typically means drier/warmer falls and potential for more winter cold air outbreaks Recent Weather Notes: Past week saw summer-like temperatures 12-16°F above normal Statewide average of 72°F (14.7°F above normal) Cold front October 5th brought localized heavy rain (1.5-2.5 inches in diagonal band from southwest to northeast Iowa) Specialty Crop Impacts: Fall warmth accelerating fall crop growth (lettuce, etc.) Extended season benefiting delayed summer plantings Discussion of rice growing in Minnesota and overwintering onion planting strategies Tips on managing fall-planted flowers to avoid early flowering Upcoming Events: High Tunnel Short Course - November 12th at Iowa Arboretum, Madrid, IA (registration now open) Topics: high tunnel peach production, transplant watering strategies, high tunnel soil health management Impact Squared Virtual Visioning Activity - November 6th, 6-7:30 PM Help inform climate tool development for small-scale and specialty crop farmers $100 Amazon gift card for participants Bonus Weather Fact: First EF5 tornado in over 12 years confirmed in North Dakota (June 2025) - last one was Moore, Oklahoma in May 2013 podcast summary generated using Claude.ai

Weather History & Forecast: 1942: Early snowfall hit Iowa on this date, with up to 4 inches accumulating in some areas Coming week: Unseasonably warm and dry with sunny days, temperatures above normal Extended outlook: Strong warm signal through early October, particularly in upper Midwest Recent Weather: Past week: 8-12 degrees above average statewide First above-average rainfall period in weeks (with the highest, 4.54", in Fort Dodge!) Eastern Iowa remained drier than western areas Specialty Crop Updates: Peppers: Good yields continuing due to warm weather; some cyclamen/broad mite issues observed in Newton area Carmen peppers: Unusual spiciness reported - growers advised to check Melons: Reduced solar radiation from cloudy, wet summer conditions may have contributed to poor season (theory posited by Jordan Lyon, Buser's Produce) Tomatoes: Splitting issues due to uneven rainfall patterns Frost Outlook: No widespread frost expected through October 11th based on dew point forecasts Warm, dry conditions may still allow nighttime cooling near normal levels Upcoming Events: October 4: Nut Growers of Iowa field day (Centerville/Ottumwa) October 7: Shimek Forestry field day (southeast Iowa) October 9: Yellow River Forestry field day (northeast Iowa) Greenhouse/High Tunnel Tip: Control weeds now to prevent pest and disease carryover through winter   Podcast Summary generated using claude.ai

• Historical Weather Moment: In 1912, Iowa experienced extreme weather swings from 104°F heat to snow flurries within just 9 days in September • Current Forecast: Unsettled weather with cut-off low pressure system bringing increased precipitation chances, potential storms with wind and small hail, but overall benign conditions • 8-14 Day Outlook: "Red bullseye" over Iowa and Minnesota indicating high likelihood of above-normal temperatures (mid-upper 70s vs normal) through September 30th • Recent Weather Events: Northern Iowa hit with 1+ inch hail reports across multiple counties; Fort Dodge area received 4+ inches of rainfall; most of central Iowa remained dry • Summer Glory Index Results: Iowa's meteorological summer rated as "fine" with SGI of 1420, held back primarily by July's high dew points and overnight lows; only 3 days reached 100°F in Western Iowa • Fall Foliage Prediction: Favorable conditions for vibrant fall colors with warm days, cool nights, and sunshine; early color changes already spotted on individual tree branches • Specialty Crop Update: Poor pumpkin harvest continues due to fruit set issues and rot problems; fall brassicas showing alternaria from earlier wet conditions but later plantings look strong; fall carrots performing well   Summary generated using Claude.ai

Weather Forecast & Climate Updates • Hot and dry conditions ahead with temperatures in low-mid 90s and heat index values in mid-upper 90s • 8-14 day outlook shows continued warmth into late September with slight chance for above normal precipitation • ENSO update: 71% chance of La Niña transition October-December, signaling potential warm and dry fall/winter This Week's Weather Recap • Chilly temperatures that felt great after a hot summer • Mostly dry conditions with under 0.4 inches for most of the state • First freeze of season recorded at Stanley, Iowa (32°F on September 7th) Specialty Crop Impacts • Pumpkins: Strong auction prices ($5-10 vs typical $2-3) but poor growing season with fruit set issues • Cucumbers: Cold damage causing unmarketable scarring at Featherstone Farm • Melons: Season ended 6+ weeks early, creating H-2A labor contract challenges for growers • Watermelons: Poor year especially in low-lying areas due to fruit rot • Flowers: Mixed reports - Rose Farm had great year, others experienced delays • Honey production: Drastically reduced to 1/5 of expected yields, indicating widespread pollinator issues Historical Weather Note • September 11, 1917: Earliest freeze on record hit eastern Iowa with temperatures as low as 30°F, causing considerable damage to corn, potatoes, and other late crops Coming Next Week • Summer Glory Index results and fall foliage outlook Podcast summary generated using Claude.ai

Weather History & Forecasts Iowa Weather History (1989): Large thunderstorms brought heavy rain to western Iowa with severe weather and brief tornadoes, causing wind damage, roof damage, and trees falling on cars 7-Day Forecast: Cool autumn weather with clear skies and below-average temperatures; best rain chances on days 4-6 due to Atlantic activity and shifted Bermuda high Climate Outlook: September 9-13 shows slightly warmer temperatures and higher precipitation chances in western Iowa; monthly outlook suggests equal temperature chances and wetter conditions statewide Weather Summary & Notable Events Past Week: Most of Iowa received below-normal rainfall (0.5" below average), except western/southwestern Iowa which saw above-average amounts Cold Snap: Some locations hit around 40°F, causing potential localized damage to sensitive plants like basil but not widespread frost damage Summer 2025 Overview: 10th wettest summer in 153 years with 18.5" total precipitation (5" above average); July was 2nd wettest on record; August was drier at 3.4" (0.75" below average) Heavy Dews Explanation Seasonal Pattern: Heavy dews occur in late August/early September due to shorter daylight hours and cooling surface temperatures Science: Earth radiates heat overnight while warm air masses remain overhead, reaching dew point and creating heavy condensation Crop Impact: Wet leaves from heavy dews can promote foliar pathogens and crop decline Specialty Crop Topics Foxtail Grass Seeds: Grower concerned about viability of mowed green foxtail; recommended germination testing with moist paper towel method Compost Management: While beneficial, compost can raise soil pH and create phosphorus excess due to 1:1:1 N-P-K ratio; rule of thumb: 1% organic matter = 20 lbs nitrogen per season Nitrogen in Rainfall: Addressed grower question about delayed flower blooming; rainfall contains minimal nitrogen (0.5-3 mg/L) compared to irrigation water nitrate levels (10+ mg/L); plant greening after rain is primarily due to improved nutrient availability from soil moisture, not atmospheric nitrogen Cover Crops: Good timing now for oats and peas establishment; winter rye timing approaching; recommend seeding when rainfall is expected Episode Summary created by Claude.ai

Weather Forecast & Conditions: Cold front moving south from Minnesota will stall over Iowa, bringing rain chances Friday-Sunday Expected rainfall: up to 1-1.5 inches in northwest Iowa, less than 0.5 inches elsewhere  Cool temperatures continuing into early September (50-60% chance of below normal temps) First overnight lows in the 40s recorded this past week Historical Weather Note: August 28, 1979: Violent F3-F4 tornado tracked 45 miles across southwestern Iowa, killing 2 people and causing millions in damage Growing Season Challenges: One grower called this "the worst growing season in recent memory" due to excessive rain and heat Watermelon season ending 1.5 months early due to persistent rainfall (14 inches over 2-3 weeks) Widespread crop diseases including Phytophthora on pumpkins, pepper anthracnose, bacterial spot, and southern rust on sweet corn Specialty Crop Impacts: Cut flower growers dealing with high soil pH (7.7) and nutrient leaching Recommendations to remove diseased peppers to prevent further spread Discussion of sprayer technology resources for disease management Looking Ahead: Hope for warm, dry fall to help struggling crops mature Next week will feature meteorological summer season review and in 2 weeks, the Summer Glory Index results Podcast summary generated using Claude.ai

What in the Weather? - August 21, 2025 Episode Summary Weather Discussion Historic perspective: August 21, 2004 saw unusually cool temps (upper 30s) in northern Iowa - opposite of current conditions Hot summer analysis: July averaged 2°F above normal with exceptional humidity (85% of days had above-average dew points) Heat index impact: Triple-digit heat index values driven more by high dew points (upper 70s-low 80s) than air temperatures Moisture source: Gulf moisture "gate wide open" with southerly winds bringing exceptional humidity to upper Midwest Forecast Weekend cooldown: Dramatic temperature drop to highs in 70s, overnight lows in upper 40s-mid 50s Extended outlook: Southeastern Iowa likely colder late August, September outlook shows warm/dry trend Precipitation: Minimal rainfall expected (0.1-0.25") with best chance Friday night into Saturday La Niña watch: Potential fall development could affect late October/November weather patterns Specialty Crop Impacts Disease issues: Rhizoctonia root rot affecting snapdragons; tomato brown rugose fruit virus causing uneven ripening Pest spotlight: European corn borer infesting dahlia stems and peppers - biological control with Trichogramma wasps recommended Growing challenges: Excessive moisture limiting planting windows; late-planted fall crops struggling to establish Crop performance: Good pepper year for some growers, but eggplant and tomato fruit set suffering from heat stress Resources Penn State cut flower production newsletter Utah State University cut flower resources

Coming in September to your favorite podcast platform: Pivot Points, a new podcast exploring the stories of farmers who have made big changes to their farms and in their lives. Follow the Pivot Points podcast to make sure you get the podcasts as soon as they are released.

Iowa's top 10 historical rainfalls • 10th Place: Sheridan (Lucas County) - 11.23 inches on August 27th, 1903 • 9th Place: Ionia (Chickasaw County) - 11.25 inches on August 9th, 2021 • 8th Place: Dumont (Butler County) - 11.28 inches on July 17th, 1968 • 7th Place: Castana Experimental Research Farm (Monona County) - 12.02 inches on July 17th, 1996 • 6th Place: Bonaparte (Van Buren County) - 12.1 inches on June 10th, 1905 • 5th Place: Hudson (Black Hawk County) - 12.28 inches on June 1st, 2000 • 4th Place: Rathbun Dam (Appanoose County) - 12.34 inches on August 24th, 2007 • 3rd Place: Le Mars (Plymouth County) - 12.41 inches on January 5th, 2009 • 2nd Place: Audubon - 12.53 inches on July 2nd, 1958 • 1st Place: Atlantic 1 NE (Cass County) - 13.18 inches on June 14th, 1998

Main Topic: "Corn Sweat" Phenomenon Definition & Media Coverage "Corn sweat" is simply a catchy term for evapotranspiration Justin Glisan was interviewed by major news outlets (Washington Post, CNN, USA Today, CBS) The phenomenon was trending during the hottest week of July 2025 during a heat dome Scientific Reality Corn releases water vapor and oxygen through transpiration (not actually "sweating") Adds 3-5% to relative humidity locally (3-5 degrees to dew point) Peak evapotranspiration occurs during corn pollination/tasseling season Iowa has 13 million acres of corn contributing to this effect Comparative Analysis Prairie grasses actually have slightly higher evapotranspiration rates than corn Corn and soybeans have very similar ET rates during peak growth Historical prairie landscape would have different hydrology and soil structure Modeling is used to understand these complex comparisons since full-scale experiments aren't feasible Weather Forecasting History First tornado warning issued in 1940s by Miller and Fawbush at Air Force base WWII and 1946 weather radar development improved forecasting capabilities 1925 Tri-State tornado killed ~700 people despite warning signs, but no communication system existed Modern forecasting balances accuracy with avoiding "boy who cried wolf" scenario Social Media & Public Education Madelynn Wuestenberg urges people to stop sharing corn sweat TikToks Working on program to fact-check weather-related social media content Emphasizes need for agricultural meteorologists with both meteorology and agronomy backgrounds Summary generated by Claude.ai

Historical Weather (This Day in History - 1993) Severe thunderstorms moved from Nebraska to western Iowa at 60 mph Wind gusts exceeded 70 mph, with 75 mph winds in Pottawattamie County destroying barns Council Bluffs received 2 inches of rain in 30 minutes causing urban flooding Des Moines recorded 83 mph wind gust 1993 was record wet year for Ames (20 inches of rain in July alone vs. 8 inches in July 2025) Current Weather Forecast Short-term (Justin Glisan) Rainfall chances continue through Friday night Cold front broke heat dome, bringing dew points down Temperatures: mid-80s through weekend, then back to 90s Minor rainfall chances early next week Northern Iowa has less rain chance as storm track moves south Expected rainfall: 3/4 inch statewide (below normal), 1.5-2 inches in southwestern Iowa Extended Outlook (Madelynn Wuestenberg) 6-10 day outlook (July 29-Aug 2): Slightly below normal temperatures in north, near normal in south; 33-40% chance above normal precipitation 8-14 day outlook (July 31-Aug 6): Continued slight chances of below normal temperatures; western Iowa slightly wetter, eastern Iowa near normal Normal temperatures: Daily highs mid-80s, lows in 60s Recent Weather Events Heat and Humidity Yesterday and prior day were hot, with cloud cover mitigating worst conditions in central Iowa Eastern Iowa experienced "dew point pooling" with dew points in upper 70s-low 80s Hottest reading: Dubuque Lock and Dam hit 95°F with heat index of 110°F Severe Weather 6 AM tornado warnings in central Iowa Tornado warnings near Maxwell and eastern Iowa Caused by remnants of mesoscale convective vortex from Kansas moving along warm boundary Rainfall Totals (Past 7 Days) Northeast Iowa: 4-4.5 inches (highest) Central Iowa: 3-3.5 inches Southwest Iowa: Trace to 0.25 inches (lowest, drought conditions persist) Specialty Crop Impacts Garlic Disease Investigation Farm in Chariton, Iowa had garlic crop with yellowing (suspected aster yellows) Testing revealed it was a virus, not aster yellows phytoplasma Cannot save seed for next year due to virus Comparison with aunt's clean stock showed dramatic difference At a different farm, possible Embellisia skin blotch observed on garlic wrappers Brassica Issues Black rot & alternaria affecting collards, broccoli, and kale Wet conditions exacerbating disease problems Nutritional Concerns Nitrogen leaching due to excessive moisture Fertilization may be necessary to supplement leached nutrients Crop Performance Issues Onions in Central Minnesota: Unexpectedly bolting across all varieties (planted from seed this spring) Zucchini: Poor fruit set, currently "worst crop of the year" candidate Tomatoes: Slow growth, fruit remaining green General pollination: Poor across multiple crops due to hot, wet conditions Heat may be affecting fruit set in tomatoes and peppers (flower abortion) Upcoming Events July 30: Cut flower field walk at River Root Farm (Decorah) July 31-Aug 1: Plant Peddler educator field day and variety day (Cresco) August 2: Grow Johnson County field day and food safety workshop August 5: Iowa State fruit and vegetable Field Day August 20: Midwest mechanical weed control field day Show Notes Hiatus announcement: No new episodes for 3 weeks (pre-recorded content only) Return date: August 21st, 2025 summary generated using Claude.ai

Weather History On July 17, 1972, slow-moving morning thunderstorms dropped 5.5 inches of rain at Sioux City, setting the all-time daily rainfall record there (still standing). Other highlights: 4.63 inches at Sac City, 3.45 inches at Humboldt. Short-Term Weather Outlook Cool air has returned after a recent frontal passage, but temperatures are forecast to increase again heading into next week. There are chances for showers and thunderstorms through the weekend. A “Ring of Fire” storm pattern will set up as a heat dome builds south over Missouri, leading to more storms along its northern edge (ridge riders/squall lines), likely north of Iowa, affecting the Upper Midwest (ND, SD, MN, WI). Medium-Range Weather Setup The bullseye of the heat dome appears over Missouri July 22–26; during this time, Iowa will see a precipitation gradient, with most rain favored in northeast Iowa. Precipitation forecast is variable, and storm placement will become clearer closer to each event. Southeast Iowa (and previously drier northern counties) have recently received significant rainfall, shifting them from "have-nots" to "haves." Ottumwa remains in moderate drought ("D1") as a stubborn dry spot. Climate Outlook 6–10 and 8–14 day forecasts show high probabilities for above-normal warmth (especially south), then continued wetness through late July. The 3–4 week outlook through August 8 gives no clear signal on temperatures, with a slight lean toward dryness in southwestern Iowa. Initial August outlooks show “equal chances” for temperature and precipitation over southern and central Iowa, a result of persistent widespread soil moisture which helps moderate heat. Atmospheric Impacts Recent wetness tamps down temperature extremes due to moist soils and increased cloud cover. The area’s high dew points indicate low atmospheric demand, reducing drought risk but potentially increasing plant disease issues. Past Week's Weather Severe weather last Friday produced two weak tornadoes in southern and eastern Iowa, with no widespread damage. Wildfire smoke from Canada arrived over the weekend after a strong cold front and wind shift to northwesterly flow. Wet conditions continued across much of the state. Specialty Crop Impacts Foliar Disease Risk Prolonged wet conditions are increasing foliar disease risks in specialty crops. Preventive fungicide programs are recommended for conventional growers, especially on brassicas (cabbage, broccoli, cauliflower). Summary of biopesticide efficacy for brassica diseases (per Meg McGrath, Cornell University): For black rot: Oxidate worked in 1 of 1 trial, Regalia in 1 of 2, copper in 4 of 5, Double Nickel in 1 of 1. For alternaria: copper is most effective. Over-use of copper risks resistance and soil accumulation; organic certification requires soil copper testing before use. For basil downy mildew: Only resistant varieties (notably the Prospera series) provide reliable control—fungicides are not effective. For powdery mildew on pumpkins and squash: Use potassium bicarbonate products like Kaligreen or Milstop (these are safer than baking soda due to plant salt sensitivity). Disease and Cost Monitoring Meg McGrath's cost-per-acre chart helps growers compare costs of biopesticides and fungicides Beet and Swiss Chard Disease Cercospora leaf spot is appearing on beet and Swiss chard leaves, making chard unmarketable. Resistant varieties like Char Bell are advised for chard. Japanese Beetle Management Listener asked about Milky Spore for Japanese beetle grub control. Dan cautions little evidence supports its effectiveness and prefers pest exclusion over soil treatments, since beetles migrate from other areas. Pheromone traps may attract more beetles than they catch—sometimes best given to neighbors to ward beetles away from your crops. Colorado Potato Beetle Resistance The second generation of Colorado potato beetle larvae has emerged. Rotate insecticide chemistries to avoid resistance (e.g., use Azera in the second generation if spinosad was used in the first). Non-chemical methods, like knocking beetles into a soapy water bucket, remain effective—plants tolerate up to ~33% defoliation before yield loss. Announcements and Events The Fruit and Vegetable Field Day at Iowa State University’s Horticulture Research Station will be held August 5th, 2:00–5:30 PM (free, with supper and registration link provided). The Plant Peddler "Educate the Educators" Day is July 31st in Cresco, with a feast and entertainment; the next day is Variety Day showcasing mature bedding plants (trade show only, not for sale). Practical Farmers of Iowa opened applications for the horticulture program coordinator position. Podcast summary generated using perplexity.ai

Recent Iowa Weather Highlights Heavy Rainfall: Rain gauges in the Des Moines area report 1–2.2 inches; some areas in western/central Iowa received up to 6 inches in the past week. Southeast Iowa remains much drier, with some locations getting less than 0.1 inch.   Historical Context: July 11, 1993: Major flooding in Des Moines, with 250,000 residents losing water after levee breaches. 1993 marked 20 out of 37 consecutive days of measurable rain somewhere in Iowa. Current Wet Stretch: Statewide rainfall is 137% of normal for July so far. Several stations have received half a month’s rainfall in just the last 10 days. Dew points remain high (60s–70s), signaling ongoing Gulf moisture. Weather Outlook Short-Term Forecast: Active weather continues for the next two days, with a chance of severe storms (supercells transitioning to linear systems). Flood warnings and flash flood watches remain in effect. After the weekend, temperatures return to the 90s, then cool down. Medium & Long-Term Outlook: July 16–20: Likely below-normal temperatures, leaning wet. July 18–24: Continued cool and wet trend. End of July: Warmer temperatures expected, with equal chances for precipitation. Southeast Iowa may remain drier than other regions. Regional Details: The "blue bullseye" for cooler weather covers eastern Nebraska, most of Iowa, Minnesota, and Wisconsin. Weather Patterns & Impacts Storm Dynamics: Stationary fronts and ample Gulf moisture are causing repeated thunderstorms. Linear wind profiles have led to more squall lines and fewer tornadoes. "Training" thunderstorms have produced localized heavy rain. Precipitation Trends: 40% of Iowa’s annual precipitation typically falls on just 10 days. High-intensity, short-duration rain events are becoming more common, often leading to localized flooding and drought in different parts of the state. National Weather Note: Texas Flooding Recent Event: Two Texas locations received 11 inches of rain in just over 24 hours. Catastrophic flooding on the Guadalupe River, with water rising 20–30 feet in under an hour. Factors: Gulf and monsoonal moisture, remnants of Tropical Storm Barry, and stalled weather systems. Similar patterns have caused flash flooding in Iowa (e.g., Clive in 2018, Des Moines metro in 2019). Specialty Crop & Pest Updates Disease Risks: Continued wetness raises concerns about foliar diseases (e.g., black rot in brassicas and cabbage). Wet conditions and heavy dews may increase disease pressure as the season progresses. Pest Observations & Management: Japanese Beetles: Active on crops like zinnias, basil, and sweet corn (can affect pollination if silk is heavily clipped). Control options: Conventional sprays (e.g., Mustang Maxx), manual removal, and using trap crops. Colorado Potato Beetle: Reports of spinosad resistance. Alternative controls: Physical removal (bucket method), azadirachtin, or biological products (though some, like certain BT strains, are hard to find). Potatoes can tolerate 33% defoliation before yield loss. Onion Thrips: High populations observed in some fields, causing silvery-white damage. Economic thresholds vary (1–3 thrips/leaf per Cornell/UMass; up to 30 per UC). Control: Multiple modes of action, increased spray volume, horticultural oils, azadirachtin, and soil treatments with fungi or nematodes. Other Notes & Events Field Days & Workshops: August 2: Field day at Grow Johnson County’s Poor Farm, covering no-till vegetable research and a short food safety workshop (counts as an annual update for PSA-trained growers). Agrivoltaic field days in Ames: Ongoing research on crops grown under solar panels, with field days every other week through September. Podcast summary generated using perplexity.ai

Iowa Weather History: On July 3, 2001, severe thunderstorms in southern Iowa produced very large hail: 2.5-inch stones at Osceola, 3-inch at Otley, and 4-inch at Truro, causing widespread and extensive damage. Recent Severe Weather Trends: Hail has been infrequent this year, with the most recent notable event in north central/northwestern Iowa a few weeks ago. The primary severe weather mode this season has been wind, with only a few pockets of hail and very few tornadoes (no tornadoes in May, five reports in June, including a landspout). Despite fewer severe storms, thunderstorms have provided good rainfall, especially in northern and western Iowa, aiding drought improvement. 7-Day Weather Forecast: Expect average summer weather: several chances for thunderstorms over the next week. Temperatures will be typical for the season, with daytime highs in the mid-80s and overnight lows in the mid to upper 60s. Rainfall (QPF) is forecast at 0.5 to 1 inch, mostly thunderstorm-driven and variable. The best chance for statewide rain is Saturday night into Sunday, with additional chances late Tuesday into Wednesday. Climate Outlook: The July outlook initially showed a large dry area from the High Plains to the Gulf, but recent wet weather reduced this to a small bullseye over Nebraska, Kansas, Missouri, and Iowa. The last ten years of Julys in Iowa have been 5–10% drier than average, influencing the forecast. The first half of July still leans wet for most of Iowa; models suggest the second half could turn drier. Past Week’s Weather: The past week was about 2°F above average for temperatures and below average for rainfall. The state is transitioning to a quieter storm track, and soil moisture has improved thanks to late June rains. Eastern Iowa, especially around Waterloo, Cedar Rapids, Washington, Wapello, Linn, and Black Hawk counties, remains drier and needs more rain. Specialty Crop Impacts: Zucchini: Squash vine borer is active and affecting small plantings; some growers report a lull in fruit set, possibly due to poor pollination (weather or varietal timing). Squash bugs: Adults are mating; now is the time to scout for eggs and treat nymphs with insecticidal soap or oils. Adults are hard to control; many growers opt to replant rather than spray. Japanese beetles: Now appearing, mostly affecting basil (culinary and cut flower types), zinnias, and grape leaves. Basil downy mildew: 'Cardinal' basil (popular for cut flowers) lacks resistance and is vulnerable. 'Thai Prospera' basil offers downy mildew resistance and may be a better filler for bouquets. Garlic: Harvest is beginning. Use the "five green leaves, sixth browning" rule to time harvest for optimal bulb quality and storage. Tomato spotted wilt virus: A grower in Kalona who lost most of his tomato crop to this virus in previous years now sees minimal infection, likely due to reduced thrips pressure. Onion thrips can also vector the virus, so monitor onions for thrips damage. Upcoming Resources and Events: Dan will share links in the newsletter on strawberry plug planting, spring broccoli variety trials, root maggot information, and upcoming field days (flower field day in Decorah, urban ag field day in Waterloo, and a native plant propagation survey). summary generated using Perplexity.ai

Weather History & Current Conditions Historical reference: June 26, 1993 - Severe hailstorms in western Iowa with golf ball to softball-sized hail caused extensive damage to crops, trees, cars, and buildings Recent weather: 150-400% of normal rainfall across southern Iowa with some areas receiving 3-8 inches (equivalent to a month's worth of rain) Heat wave anomaly: Unusual combination of high 90s temperatures, high humidity, and sustained strong southerly winds for 24-36 hours - described as a "black swan event" Record temperatures: Many stations recorded daily record warm overnight low temperatures that didn't allow for cooling Weather Forecasts Short-term: Continued unsettled pattern with thunderstorms and slight severe weather risk in north-central to northeastern Iowa Coming week: Heavy rain potential (1-2 inches), cooler 80s tomorrow, then back to low 90s with Sunday thunderstorms followed by quieter conditions Extended outlook: 6-10 and 8-14 day forecasts show near normal temperatures with continued wet signal; July outlook leans warm statewide with slight dry tendency in western Iowa Sweet Corn Season & Pest Management Sweet corn timing: First harvest expected within days - Roger VanDonselaarr (Prairie Produce, Grinnell) and Hilltop Farm (Dallas Center)  Production methods: Early growers use clear plastic mulch and row covers to accelerate growth Corn earworm challenge: Moths present requiring spray applications every 2-3 days, but wet conditions prevent field access Quality standards: Zero tolerance for worms in commercial sweet corn due to consumer expectations and processing requirements Drone spraying: Some growers adopting drone technology to overcome wet soil limitations, though wind conditions still restrict applications Disease Management & Crop Care Disease scouting tips: Stay out of wet fields to prevent disease spread Start with youngest, healthiest plants before moving to diseased areas Use clean clothes, tools, and boots daily Disinfect pruners between plants Current diseases observed: Bacterial leaf spot in parsley/cilantro and black rot in brassicas Garlic Production Scape removal timing: Research shows removing scapes as early as possible (when just emerged) produces largest bulbs Manual vs. mechanical removal: Hand removal preferred as mowing can remove leaves and reduce bulb size by 15% Market considerations: If selling scapes, wait for full curl; if maximizing bulb size, remove immediately Upcoming Events July 1: Plant diagnostic clinic at Twin County Produce Auction, Kalona (9-11 AM) July 8: Rodale Field Day at Midwest Organic Center near Cedar Rapids - featuring autonomous robotic ag tools July 31: Educate the Educators Day at Plant Peddler, Cresco August 1: Variety Day trade show at Plant Peddler End of July: Cut flower field day at River Root Farm, Decorah End of August: Midwest Mechanical Weed Control Field Day, Ames summary generated using claude.ai

Iowa Weather History: On June 19, 1996, severe thunderstorms produced very large hail in northwest Iowa, with a 3.5-inch stone near Hinton (Plymouth County) and a 4.5-inch stone at Cushing (Woodbury County), causing $200,000 in damage to vehicles and buildings. 7-Day Weather Forecast: Iowa is entering a "blast furnace" pattern: temperatures will soar 15–20°F above average, with highs in the 90s to upper 90s and overnight lows in the mid to upper 70s. Persistent high overnight lows will make it difficult for people and plants to recover. Strong southwesterly winds will continue, bringing high dew points and Gulf moisture. By days 4–6 (early next week), the northwestern two-thirds of Iowa could see 2–5 inches of rain, especially in western Iowa, which needs relief from drought. Climate Outlook: The 6–10 day forecast shows the heat shifting east, with a tighter temperature gradient and continued potential for heavy rainfall, especially in northern Iowa. The 8–14 day outlook keeps a warm and wet signal, which is positive for the wettest month of the year after recent dryness. The 3–4 week outlook still leans warm, with no clear signal on rainfall. The initial July outlook (issued June 19) leans slightly warm statewide, with a slight lean dry in the western third of Iowa. Recent Weather and Notables: The past week was slightly warmer than average with an unsettled pattern of pulse and “popcorn” thunderstorms across the state. Severe weather ingredients did not come together for widespread severe storms, but there was a landspout tornado in eastern Iowa. Landspouts are weaker, photogenic tornadoes (a step above dust devils), typically anticyclonic, and distinct from stronger tornadoes. Specialty Crop Impacts: Hot weather is negatively affecting broccoli development, leading to issues like “brown bead” (brown florets) and heat-delayed buds. Brown bead can be caused by hot, humid nights; broccolini is less susceptible and can regrow after harvest. Hollow stem in broccoli may result from fast growth due to excess nitrogen and water, not just boron deficiency. Tighter in-row spacing and careful nitrogen management can reduce hollow stem. Boron deficiency causes brown, dead cells lining the hollow stem, while fast growth causes uniformly green or white hollows. Boron should be mixed with other powders for uniform soil application to avoid toxicity. Some broccoli varieties (e.g., Green Magic) are more prone to hollow stem than newer ones (e.g., Eastern Crown). Heat can also cause uneven, lighter green patches in broccoli heads (heat-delayed buds). Brown bead does not grow out, but heat-delayed buds sometimes do Cabbage White butterflies and their caterpillars are active. BT (Bacillus thuringiensis) sprays are effective when caterpillars are first seen, especially on new growth and broccoli heads. Rotate BT with other organic insecticides if resistance is suspected. Cabbage moth caterpillars can hide inside broccoli heads, making washing difficult. Summary created using Perplexity.ai

Iowa Weather History June 13, 1976: an F5 tornado near Luther, Iowa, was one of the largest in state history. The tornado, nearly a mile wide, spawned multiple satellite tornadoes and caused widespread destruction between Boone and Ames, demolishing over 60 homes and 300 farm buildings. Charles Barthold’s iconic photographs of the event contributed to tornado science and earned him a Peabody Award. 7-Day Weather Forecast Expect continued warmth with a risk of extreme heat in the coming week. An active precipitation pattern is forecast, with widespread rain likely. Most of Iowa should receive at least an inch of rain between June 12–19; northern areas may get up to 2 inches, especially with thunderstorms. The Climate Prediction Center’s outlooks (6–10 day, 8–14 day, and 3–4 week) all lean toward above-normal temperatures and slightly above-normal precipitation. There is a slight risk for extreme heat (June 19–21) and heavy precipitation (June 19–22, especially in northern Iowa). Recent Weather The past two weeks were cooler than normal, averaging 65°F (2–4° below normal). On June 11, hailstorms hit northern Iowa (Palo Alto, Kossuth, Hancock Counties), causing severe crop damage and total losses in some corn and soybean fields. Specialty Crops Impacts Aster Yellows in Garlic and Other Crops: Aster leafhopper infectivity for aster yellows has jumped from near zero to 15–20% in Michigan, exceeding last year’s rates. Growers should watch for symptoms in garlic, flowers, and lettuce. One Iowa garlic grower observed premature yellowing and is testing for the disease; comparison with seed garlic from another location suggests possible infection. Squash Yellowing (B Gene): Yellow leaves in squash during cool weather may be due to the B gene, which breeders retain for its positive effects (fruit color, yield, virus resistance). The B gene can be identified by a yellow stem on yellow squash. Onion Thrips: High thrips numbers reported in onions and mulberries. Thrips are tough to control; Dan recommends using azadirachtin (from neem), horticultural oil, a spreader-sticker, soil-drench nematodes, and mycopesticides (Beauveria bassiana). Control is important because thrips damage increases storage rots. Aphids: Aphids can multiply rapidly, especially under row covers. Dan suggests treating transplants with insecticidal soap (e.g., M-Pede) before planting and repeating the spray after five days. In the field, use water sprays, insecticidal soap, oils, and azadirachtin. Tank-mix treatments after jar testing. Attract beneficial insects with sweet alyssum and other flowers, especially in tunnels or greenhouses. Squash Vine Borer: The pest is now active in central Iowa. Remove row covers from flowering squash, scout for eggs at the stem base, and use BT sprays or manual removal of larvae. Large fields are less affected; small plantings are at greater risk. Tomato Yellow Shoulder Disorder: This disorder is more common in hot weather and is linked to potassium deficiency and high fruit temperatures. Dan recommends ensuring adequate potassium and using shade cloth in high tunnels to keep fruit shoulders cool. Some cultivars are more susceptible. Podcast summary generated using Perplexity.ai

Iowa Weather History On June 4, 1998, sleet and trace ice were reported in Rock Rapids, northwestern Iowa—the only official winter precipitation recorded in Iowa in June; none in July or August. 1997–1998 was a strong El Niño year, noted for heavy precipitation events. Recent and Upcoming Weather Unsettled weather with rain and severe storms in eastern Iowa over the past week. Statewide air quality alert due to wildfire smoke from Canada, reducing solar radiation and lowering temperatures by 1–2°F. Transitioning to a warmer, drier pattern with scattered rain chances. Three- to four-week outlook: warmer than normal, but precipitation outlook is uncertain (equal chances of above, below, or normal rainfall). 8–14 day hazards outlook: slight risk of high temperatures (June 12–17) and heavy precipitation (June 11–14). Storm and Precipitation Recap Severe weather affected Texas, Oklahoma, Missouri, and southeast Iowa. Tornado reported in Kansas City; unconfirmed tornado in Fort Madison, Iowa, possibly derailing a train. Widespread rainfall: up to 2 inches in southeast Iowa, 2–2.5 inches in north-central and northwest Iowa, at least a trace in central Iowa. 80% of Iowa received at least half an inch of rain. Temperature Trends Last week: statewide average temperature 2.4°F below normal. Earlier in May: above normal temperatures, then a cool period. Meteorological Spring Recap (March–May) Precipitation: North-central Iowa: 114% of normal (1.4 inches above average). Southwest Iowa: 66% of normal (3.5 inches below average). Statewide: 92% of normal (about 1 inch below average). South-central and southwest Iowa: 5–6 inches below average, with ongoing drought. Temperature: Central to eastern and southern Iowa: top 20 warmest springs on record (since 1895), 1.5–2.4°F above normal. Statewide: 1.7°F above average. Severe Weather: March: 1 tornado (average is 2). April: 10 tornadoes (average is 6). May: 0 tornadoes (first time since 2010 with no May tornadoes). 2024 had 59 tornadoes in April and 47 in May—much more active than 2025. Daytime vs. Nighttime Warming: March: daytime highs 9.5°F above average, overnight lows 3.1°F above average. April: daytime highs 1.5°F above average, overnight lows 1.1°F above average. May: first half 4–6°F above average, second half cooler. Specialty Crop Impacts Wind and Erosion: Sandy soils in southeast Iowa caused sandblasting of young melons, requiring replanting. Cover crops helped reduce erosion. Pests: Moist conditions favored slugs and roly-polies (pill bugs), which damaged pepper leaves. Earwigs were problematic for dahlias. Sluggo Plus (iron phosphate with spinosad) is labeled for these pests, but efficacy is uncertain. Hay Harvest and Pests: Hay harvest displaces potato leaf hoppers, which then move to green beans and potatoes. Leaf hoppers are difficult to manage due to large populations. Garlic: Garlic scapes are emerging. Removing scapes increases yield by about 15%. Garlic scape anthracnose (a disease) can occur—remove affected scapes to prevent spread. Aster leaf hoppers and aster yellows disease: this year, no positive disease tests in Michigan (last year, 4–11% positive). Flowers: Campanula and feverfew recently bloomed. Dara and volunteer rudbeckia expected to bloom soon. Summary generated by Perplexity.ai and edited by Dan Fillius

Iowa Weather History 1906 Historical Frost: Late season statewide frost on May 28th with temperatures dropping to 30-32°F across multiple Iowa cities, though crop damage was minimal due to brief duration 2021 Comparison: Similar late freeze event occurred on May 29th with 37°F statewide average (13° below normal) Recent Frost Data: Last frost dates varied by location - Sibley (April 21st), Ames (April 12th), Keokuk (April 9th), though Mason City hit 32°F as recently as May 20th Weather Forecast & Climate Trends Short-term: Nice weekend weather with 70s-80s temperatures, some scattered showers and thunderstorms Long-term outlook: Moving toward more active storm pattern with warmer and wetter conditions expected Growing season: Expanding by 10-15 days due to climate trends, with later fall freezes and earlier spring thaws Moisture transport: Southern states' wet conditions could benefit Iowa through Gulf moisture transport mechanisms Recent Weather Conditions Memorial Day weekend: Quieter weather with temperatures 6-8°F below average Soil conditions: Persistently moist and cool, excellent for plant establishment Spring assessment: Very comfortable conditions, though not quite as ideal as 2024 when no irrigation was needed Specialty Crop Impacts & Pest Management Positive Conditions Excellent plant establishment due to consistent moisture No irrigation concerns for getting crops started Good conditions for transplant survival Potential Issues Blossom end rot risk: Persistent wetness reduces water movement and calcium transport in tomatoes Weed pressure: Moist conditions favor rapid weed growth Active Pests to Monitor Colorado Potato Beetle: Now active based on degree day models, targeting potatoes and eggplants Seed Corn Maggot: Second generation emerging, threatens direct-seeded crops like beans, corn, cucumbers Slugs: Increased activity in moist conditions, causing characteristic rasping damage Roly-polies: Higher populations in high organic matter soils may damage plant stems Management Recommendations Use row covers for newly planted eggplants and direct-seeded crops to protect from Colorado Potato Beetle, flea beetles, and seed corn maggot. Scout for Colorado potato beetle eggs and larvae Hand removal and soapy water treatments for organic pest control Monitor for slug damage patterns (round holes with scraped areas) Stay vigilant about weed management during optimal growing conditions Episode Summary generated by Claude.ai and edited by Dan Fillius

Weather History: In 1873, a deadly tornado tore through southeastern Iowa, affecting Keokuk, Washington, and Louisa counties before moving into Illinois. The storm produced very large hail (up to 4.5 inches in diameter), killed 8 people, and injured at least a dozen others. This event prompted the first detailed tornado damage survey in Iowa, conducted by the U.S. Army Signal Corps. 7-Day Weather Forecast: Temperatures are expected to remain cool for the next week. Rain chances increase as the weekend approaches, with the best chance for precipitation Sunday night into Monday. The following week will be less active Climate Forecast: 6–10 Day Outlook (May 27–31): Cooler temperatures expected in the south, near normal in the north, and likely below-average rainfall statewide. 8–14 Day Outlook (May 29–June 4): The drier signal is enhanced, and temperatures are expected to be warmer than normal. 3–4 Week Outlook (mid-June): The outlook leans warm and wetter, suggesting a shift to a more active weather pattern as summer approaches. Past Week of Weather: The past week was notably cooler and wetter than usual, with 3–4 inches of rain along the I-35 corridor and surrounding counties. Des Moines International Airport recorded 4.84 inches, the highest in the state. Temperatures were about 5°F below normal. Overnight lows dipped into the 40s, which is chilly for late May Other Weather/Climate Discussion Topics: Wind and Hail: Northern Iowa experienced strong sustained winds (37–39 mph) and gusts up to 52 mph. Hail up to 2 inches was reported in Grand River (Decatur County) and Osceola. Wind Damage: Growers in northern Iowa reported significant losses of plastic mulch beds due to high winds. Wind erosion was also noted in sandy soils in southeastern Iowa. Weather Impacts on Crops: High winds caused physical damage to plants (broken leaf petioles, windblown soil particles), and some farms reported unusual leaf spotting, possibly from wind or chemical drift. Drift investigations are ongoing in affected areas. Precipitation and Irrigation: The recent rains improved abnormally dry conditions, but growers are reminded to water in new transplants as their roots are not yet established. Weeds are expected to germinate rapidly, so timely cultivation is encouraged. Specialty Crops Impacts: Wind Damage: Growers lost plastic mulch beds and experienced wind erosion, especially in northern and southeastern Iowa. Leaf Spotting: Multiple crops (potatoes, radishes, tomatoes, cabbage, Swiss chard, cucumbers) showed inter-veinal necrosis, likely due to wind or desiccation, not herbicide drift. Weed Management: Recent rains will trigger weed germination, so growers are advised to cultivate early at the white thread stage. Cold Weather Effects: Cool temperatures can increase cat-facing in tomatoes and blossom end rot in susceptible crops. Growers are reminded to monitor for these issues if crops are flowering. Irrigation: Irrigation is less necessary after recent rains, but new plantings still require watering. Flower Crops: Rain can damage open blooms, but many flowers are harvested in the bud stage. Peony growers are drying blooms before cold storage to prevent moisture issues. Listener Engagement: Listeners should share their experiences and the impact of the podcast on their growing decisions, especially if they can quantify the financial benefit of advice received   Summary provided by perplexity.ai