I caught up with Dr. Ajay Nair at the 2026 Farm Progress Show in Boone, IA. He shared with me his vision for Horticulture at Iowa State University and in the state of Iowa.

00:00:08 — Welcome to What in the Weather?, recorded from the Farm Progress Show.

00:00:33 — Iowa weather history: the damaging, unusually early statewide frost of September 1, 1859, following late spring frosts and affecting crops including corn, buckwheat, and sorghum.

00:02:04 — Week-ahead forecast: hot, humid conditions, with "ridge rider" thunderstorms bringing a localized risk of heavier rain, especially across northern and northwest Iowa.

00:03:10 — Heat Dome "Fiero" ;-) discussion: a persistent ridge favors heat and relative dryness farther south, while storm tracks ride around its northern edge.

00:04:16 — Extended outlook for September 7–13: above-normal temperatures favored across Iowa, with near-normal precipitation expectations.

00:04:47 — Seasonal market note: continued summerlike heat may support watermelon demand longer than typical fall-oriented sales.

00:06:09 — Preview of next week's meteorological summer recap and the Summer Glory Index outcome.

00:06:33 — Last week's Iowa weather: scattered rain and storms in northern Iowa, dry conditions in several southern areas, a high of 96°F at Lamoni, a low of 48°F at Lake Park and Spencer Municipal Airport, and Rock Rapids' 1.3-inch precipitation total.

00:07:35 — Vegetable crop update: timing for oats-and-peas cover crops, plus considerations for daikon radish and brassica disease management.

00:09:08 — Disease observations in watermelon and brassicas: possible gummy stem blight in watermelon and reports of Xanthomonas leaf spot and black rot in kale, Brussels sprouts, and cabbage.

00:10:48 — Randall Vos joins from the Farm Progress Show to discuss fruit-crop conditions across Iowa.

00:10:56 — Strawberry and tree-fruit season review: weather extremes, frost, rain, disease, uneven fruit set, and thrips pressure contributed to a challenging year.

00:12:10 — Fall raspberries: generally benefiting from adequate moisture, though current heat may cause stress and drooping.

00:12:36 — Moisture-gradient impacts on fruit crops: lower disease pressure in northwest Iowa vineyards versus substantial foliar downy mildew concerns elsewhere.

00:14:07 — Early grape harvest and heavy bird pressure in vineyards, including challenges from robins, starlings, orioles, and turkeys.

00:14:52 — Possible bird damage in tomatoes and how rain can accelerate rot after fruit is pecked.

00:15:38 — High Tunnel Short Course announcement: November 11 at the Iowa Arboretum, with speakers Christa Alexander, Judson Reed, and T.D. Holub covering high-tunnel systems, fertility, cover crops, construction, and crop production.

00:16:42 — Closing and invitation to tune in next week for the meteorological summer recap.

summary generated using Perplexity.ai

Find full show notes at https://www.extension.iastate.edu/commercialhort/82726-notes-what-weather

00:00:32 Iowa weather history: Heavy thunderstorms in 1903 produced extraordinary rainfall totals across southern Iowa, including an unofficial 14.61 inches at Woodburn.

00:01:26 Weather trivia: What causes the reddish, coppery appearance of the Moon during a lunar eclipse?

00:02:00 Weekly forecast: A quieter storm track overall, better rain chances Saturday, slight chances early next week, and temperatures about 5 degrees above normal.

00:02:33 Climate outlook: A warmer-than-normal start to September is favored, while precipitation is expected to be near normal statewide. Southern Iowa faces a slight risk of extreme heat during the September 3–9 period.

00:04:28 Seasonal outlook and El Niño discussion: The hosts examine the September–November outlook, the developing Pacific signal, and how climate models use analogs and trends.

00:06:08 Past-week weather recap: Pleasant temperatures, cool nights, limited rainfall in parts of Iowa, and a reminder to credit the Iowa Environmental Mesonet and Daryl Herzmann when using IEM data. https://mesonet.agron.iastate.edu/onsite/features/cat.php?day=2026-08-27

00:07:52 Iowa temperature and precipitation extremes: Rock Rapids reached 90°F, while Spencer Municipal Airport and Lake Park fell to 47°F; Boone recorded the week's highest precipitation total.

00:08:59 Lunar eclipse viewing: Details on the August 27 deep partial lunar eclipse, including peak viewing at 11:12 p.m. Central Time and 96.3% coverage at maximum eclipse.

00:10:19 Specialty crop impacts: Powdery mildew management, late-season pumpkin guidance, and a diagnosis of Xanthomonas leaf spot in Lacinato kale.

00:12:52 Managing Xanthomonas leaf spot: Resistant cultivars, copper-based treatments, removal of affected leaves, sanitation, crop rotation, and hot-water seed treatment for brassicas.

00:14:33 Wet-season crop challenges: Dan discusses troubleshooting difficult field conditions for a northeast Iowa grower and compares the challenging 2026 season with 2025.

00:15:04 Farm Progress Show preview: The team will record next week's episode from Boone, with Dan staffing the horticulture booth and Madelynn staffing the weather booth featuring IEM and CoCoRaHS.

00:15:48 Trivia answer

00:16:39 Rayleigh scattering explained: Why the sky is blue, and how atmospheric gases scatter light.

00:17:15 Atmospheric moisture and fluid dynamics: A discussion of water vapor's small but important role in weather and the atmosphere as a fluid.

00:18:27 Tornado safety follow-up: Why seeking shelter under an overpass is unsafe, including wind acceleration, debris hazards, and traffic congestion risks.

00:21:09 Closing remarks and a reminder to join the hosts next week for an episode recorded at the Farm Progress Show.

summary generated using perplexity.ai

[00:00:51] Iowa weather history for August 19: A destructive 1898 severe-weather event brought straight-line winds, hail, heavy rain, property damage, and fatalities across northwestern Iowa.

[00:02:00] Why thunderstorms can occur overnight and in the early morning: Justin explains the role of the nocturnal low-level jet, moisture transport, ridge riders, and heat-dome patterns.

[00:03:55] Weather trivia: Is it safe to park beneath an overpass during a storm?

[00:04:37] Short-term forecast: Storm chances return through Friday, followed by quieter, seasonable weather over the weekend and into early next week.

[00:05:26] Extended outlook: Iowa has increased odds of above-normal temperatures in the 8-to-14-day period, while precipitation odds remain near normal.

[00:06:45] Heat dome discussion: The group explains persistent blocking highs, why the current heat dome is lingering, and jokingly suggests naming it "Fiero."

[00:07:36] Three-to-four-week outlook: Equal chances for temperature and precipitation across most of Iowa, with limited areas leaning warmer or drier.

[00:08:35] Hazards outlook: No hazards are forecast for Iowa, though parts of Nebraska, Kansas, and Missouri face a slight risk of hazardous heat.

[00:10:05] Past-week weather recap: Storms became more localized late in the week, after Iowa experienced its wettest week of the year to date.

[00:10:30] Iowa rainfall and temperature extremes: Discussion of statewide precipitation averages, Wapello's 8.76 inches of rain, Rock Rapids' 0.13 inches, and temperatures from 51 to 94 degrees.

[00:14:05] El Niño update: Climate Prediction Center probabilities continue to indicate a strong El Niño event, with potential implications for late fall and winter.

[00:15:10] Specialty crop impacts from recent rain: Tomato cracking, melon splitting, harvest timing, rot, and insect issues following heavy rainfall.

[00:16:47] Powdery mildew in squash and zucchini: Scouting, curative treatment options, resistant varieties, pumpkin-handle impacts, and managing disease before harvest.

[00:19:41] Squash bug management: Identifying vulnerable nymphs, spray options, timing around eggs and hatch, canopy coverage, and cautions when mixing pesticide products.

[00:22:21] Cucurbit yellow vine decline: Yellowing symptoms, adult squash bugs as disease vectors, and end-of-season squash bug management.

[00:23:09] Greenhouse Short Course: Information on the September 16 event at Reiman Gardens for ornamental greenhouse growers.

[00:23:43] Project Monarch Science app: How Bluetooth-enabled monarch tags and citizen-science observations help researchers track migration success.

podcast summary generated using perplexity.ai

00:00:25 — Iowa weather history: two violent 1974 tornadoes caused F4 damage in eastern Iowa.

00:01:31 — Weather trivia asks listeners to identify the leading cause of weather-related fatalities in the United States.

00:01:51 — Near-term forecast: an active "ring of fire" pattern brings widespread thunderstorm chances for the next four to five days, followed by a quieter, seasonable start to next week.

00:02:29 — Rainfall outlook and forecasting explained: model ensembles suggest broad totals of at least 1.5 inches, with isolated 3–4 inch amounts possible from central to eastern Iowa; local thunderstorm totals will remain highly variable.

00:05:18 — Extended outlook: Aug. 19–25 is favored to be warmer than normal in Iowa, with near-normal precipitation; the late-August/early-September outlook leans slightly drier.

00:06:44 — The team explains how Pacific monsoon moisture, the jet stream, and emerging El Niño conditions may contribute to Iowa's humidity and heavy-rain potential.

00:09:08 — El Niño update: European model projections show a potential very strong event later this year, though the hosts emphasize uncertainty and promise a fuller winter-focused discussion.

00:13:37 — Derecho and severe-weather recap: a damaging line of storms crossed eastern Iowa and continued through the Ohio Valley, with wind gusts up to 75 mph near Independence and two reported tornadoes in Delaware County.

00:15:19 — Past-week Iowa conditions: eastern Iowa saw tornado, hail, wind, crop, tree, and building damage; Nashua recorded 3.04 inches of rain, while Rock Rapids had only a trace.

00:16:52 — Recent temperature and humidity context: highs reached 94°F, Spencer fell to 47°F overnight, and the hosts compare this summer's heat and dew points with 2025.

00:18:46 — Specialty-crop update: growers seeking heat-tolerant broccoli varieties are directed to Cornell's Eastern Broccoli Project research.

00:20:14 — Corn rootworm beetles are replacing Japanese beetles as a concern for flowers, pumpkins, and sweet corn; exclusion netting or bags are the most pollinator-safe control options for cut-flower growers.

00:22:51 — Watermelon harvest challenges after heavy rain: excessive moisture can cause splitting, while growers must balance harvest timing, maturity, rind development, and variety-specific traits.

00:25:18 — Hail damage report from Algona: penny-size, likely wind-driven hail damaged zucchini and pumpkins; photos will be included in the show notes.

00:26:32 — Upcoming events: Midwest Mechanical Weed Control Field Day in Michigan (Sept. 16), Appropriate Technology Field Day in Kentucky (Aug. 25), Great Lakes Tek Flex in Michigan (Sept. 10–11), and the 40th-anniversary Hort Friday field day in Ames (Sept. 26).

00:29:25 — Additional event reminders: High Tunnel Short Course on Nov. 11 and the Southeast Research Farm Field Day in Crawfordsville on Sept. 10.

00:29:44 — Trivia answer

podcast summary generated using Perplexity.ai

[00:00:08] August 5 Iowa weather history segment, including a severe 1989 thunderstorm complex and derecho discussion.

[00:01:35] Madelynn shares the weather trivia question: Does Iowa get more than 40% of its annual precipitation in its 10 wettest days?

[00:02:03] Justin gives the upcoming forecast headline: rain chances easing, then a return to mid- to upper-80s temperatures.

[00:05:03] Madelynn reviews the 8-to-14-day and one-month Climate Prediction Center outlooks, which lean warmer and wetter for parts of Iowa.

[00:06:14] The team discusses heavy precipitation risk in eastern Iowa, wet soils, flash flooding concerns, and ridge-rider storm potential.

[00:07:56] Madelynn summarizes the past week's weather shift from hot and humid to cooler, pleasant conditions with soft rains across much of the state.

[00:10:23] Justin shares recent weather extremes, including the hottest location, coolest overnight lows, and top precipitation totals.

[00:11:21] The hosts talk about heavy rain and training lines in southern and central Iowa, plus flash flood concerns and rainfall extremes.

[00:12:51] Dan moves into specialty crop impacts, covering watermelon harvest progress and melon ripening in Iowa.

[00:13:57] Dan discusses broad mites in peppers, including symptoms, scouting, and management challenges.

[00:15:16] The conversation shifts to thrips damage in gladiolus, possible species involved, and treatment considerations.

[00:18:29] Dan explains the difference between truss tomatoes and standard tomato varieties, using a grower example and seed sources.

[00:20:30] Dan notes the first Wisconsin report of beet rhizomania and explains why it matters for beet production.

[00:21:15] The episode includes a listener question about Japanese beetles, their life cycle, and when they should disappear.

[00:23:20] Madelynn answers the trivia question

00:00:08–00:02:00: Dan and Justin discuss the first recorded tornado damage in Iowa history from 1804.

00:02:00–00:04:05: The team previews the coming week's forecast, including heat, muggy conditions, wildfire smoke, and a rain system that could bring widespread rainfall.

00:02:41–00:03:55: Madelynn introduces the weekly trivia question about which RAGBRAI year had the most hours with a heat index above 85 degrees, with a note that Des Moines data is being used as a proxy.

00:04:05–00:08:24: Madelynn walks through the 8–14 day Climate Prediction Center outlook, the hazard outlook, and the three-to-four-week outlook, highlighting above-normal temperatures, near-normal precipitation, and some drought concern.

00:07:39–00:08:24: Dan adds harvest timing advice for potatoes, onions, and garlic ahead of potential rain, and mentions the upcoming final August monthly outlook.

00:08:25–00:10:12: Madelynn summarizes the past week as "moist and on fire," describing heat, humidity, dense fog, and a fire at the Agristar meat processing plant in Postville.

00:10:12–00:11:20: The hosts review extreme heat statistics for Des Moines, including a 1936 record and the near-record heat index from July 27, 2026.

00:11:21–00:13:13: Justin shares weekly weather superlatives, including the statewide high, low, and wettest location, and the hosts correct a questionable Spencer low-temperature reading.

00:13:14–00:16:06: Dan discusses tomato botrytis issues in a high tunnel, possible management options, and whether removing infected plants could spread spores.

00:16:06–00:18:10: Dan shares that he tested positive for Cyclospora, explains the infection route, and talks about antibiotics and sun sensitivity.

00:18:10–00:20:38: The conversation turns to garlic viruses, clean seed production, and how virus-free seed can improve yields.

00:20:46–00:22:24: Dan discusses farm decision-making and labor tracking using the "Know Your Cost to Grow" approach to evaluate equipment investments.

00:22:45–00:23:31: Dan plugs Farm to Table for All, a local produce-purchasing and food-distribution effort in the Des Moines area, and mentions an upcoming event.

00:23:35–00:24:14: Madelynn reveals the trivia answer

00:24:25–00:25:18: Dan closes with thoughts on tailwinds and headwinds during RAGBRAI, congratulates riders, and signs off for the week.

summary generated using Perplexity.ai

00:00:31 Iowa weather history: July 23, 2010 flooding and Delhi dam failure

00:02:03 Trivia question on severe weather warnings in Iowa

00:02:39 Weekly forecast: hot, humid conditions with highs in the mid to upper 90s

00:03:02 Rain outlook: scattered storms, potential for localized heavy rain, low severe risk

00:04:31 Climate Prediction Center outlook: above-normal temps, below-normal precipitation trends

00:05:55 Extended outlooks: limited signals; slight precipitation increase for August

00:06:48 Recent weather recap: storms, uneven rainfall

00:07:58 Wildfire smoke impacts across the Midwest and Iowa

00:10:33 Discussion on repeated heavy rainfall in central Iowa and storm patterns

00:13:44 Temperature extremes: recent highs above 100°F and questionable low temperature readings

00:16:30 Precipitation totals: Osage leading rainfall; continued dryness in northwest Iowa

00:18:51 Home weather station experiment: large discrepancies in rainfall measurements

00:21:50 Specialty crop segment begins

00:22:06 Horticulture Field Day announcement (July 29 in Ames)

00:22:54 Purslane weed management: growth habits and control strategies

00:25:09 Bacterial canker in tomatoes: symptoms and prevention

00:26:17 Rapid crop development due to heat and degree day accumulation

00:26:40 Cyclospora outbreak: food safety considerations and transmission

00:30:12 Trivia answer revealed

Summary generated by Perplexity.ai

It's Swass season, y'all.

00:00:49 – This Day in Iowa Weather History: the 1984 temperature swing from 35°F frost at Elkader to 100°F at Shenandoah in 24 hours

01:19 – Weekly trivia question introduced: what's Iowa's record 24-hour precipitation total?

03:15 – Weather forecast headline: slight severe storm risk overnight, hot and mostly dry week ahead with highs in the low-to-mid 90s

04:12 – Extended climate outlook: hot and dry pattern dominates 6-10 day, and 8-14 day outlooks, with a Level 3 heat risk for northwest/western Iowa July 10-14

08:41 – Past week's weather recap: multiple tornado reports, wind/hail damage, and significant flash flooding over the July 4th weekend

11:09 – Breakdown of extreme rainfall totals from the holiday weekend, including a 12+ inch radar-estimated total near Elkhart and a 10.99" official CoCoRaHS reading in Polk City

11:16 – Guidance on food safety for flooded fields, including National Organic Program waiting periods (90/120 days) and FSMA considerations

15:16 – Why CoCoRaHS gauge density matters, plus a call for listeners to join the network

18:49 – Discussion of why the storm's rainfall was under-forecasted, tied to an upper-level disturbance disrupting the priorheat dome

22:04 – Revisiting "100-year" and "1,000-year" flood terminology and annual exceedance probability

24:23 – Specialty crop impacts: Phytophthora risk in wet cucurbit/pepper fields, growth-regulator herbicide drift symptoms in tomatoes/peppers, and distinguishing drift damage from broad mite infestation

27:03 – Tip on sanitizing surfaces efficiently using a hose-end sprayer

episode summary generated using claude.ai

Resources:

• VDIFN Tool
• Ari's tutorial on YouTube for visual aids
• VDIFN User's Manual
• Crop Risk Tool

[00:00:08] Dan introduces the episode, recorded in advance while he's away, featuring guest Ari Abbrescia, Organic and Sustainable Agricultural Outreach Specialist with UW-Madison Extension.

[00:00:48] Ari provides an overview of the VDIFN (Vegetable Disease and Insect Forecasting Network), including its creators — Dr. Amanda Gevens, Dr. Russ Groves, and Ben Bradford — and its role in supporting integrated pest management across the upper Midwest.

[00:02:06] Dan and Ari dig into a real-world example: why VDIFN appears to show flea beetles absent in Iowa when growers in southern Minnesota are already seeing them.

[00:03:36] Explaining the difference between Fahrenheit degree days (FDD) and growing degree days (GDD), and what those values mean within the flea beetle model.

[00:04:50] Ari clarifies that the VDIFN flea beetle model tracks the first hatched generation — not overwintering adults — which explains the apparent gap between model output and field observations.

[00:07:08] Key takeaway: VDIFN measures risk for damage, not pest presence — an especially important distinction when interpreting disease models like late blight.

[00:07:28] Dan shares how he wants to use VDIFN as a scouting lead-time tool for growers, and discusses Spinosad as a management option against adult flea beetles.

[00:08:42] Ari walks through the seed corn maggot model as a strong example of how VDIFN can directly inform planting timing decisions based on Fahrenheit degree day thresholds.

[00:10:18] Discussion of the early blight model for tomato, including how to use the biofix date and P-day accumulation to time preventative fungicide applications.

[00:11:14] Ari explains what P-days (physiological days) are and how they relate to degree days and disease severity tracking.

[00:14:31] Introduction of the Crop Risk Tool — a newer, still-developing tool built by Ben Bradford that allows users to save named locations, upload CSV field lists, and view risk across multiple models for specific sites.

[00:15:59] A key advantage of the Crop Risk Tool: it includes a 14-day NOAA-based forecast, allowing growers to look ahead and plan management decisions proactively.

[00:17:37] Comparing the two tools — VDIFN excels at visualizing spatial patterns and the movement of pest risk across the landscape; the Crop Risk Tool excels at site-specific, forward-looking risk assessment.

[00:19:23] Dan and Ari share a common wish-list feature: the ability for growers to select and view only their key pests and diseases for a saved location, rather than toggling through categories. Ari adds that text alerts are also a dream feature in early development.

[00:20:10] Dan notes that squash bugs and cucumber beetles are absent from VDIFN, sparking a discussion about overwintering adult pests and the diseases they vector, including bacterial wilt and squash mosaic virus.

[00:21:05] Conversation turns to Western flower thrips and onion thrips — including uncertainty about whether VDIFN's thrips model covers one, the other, or both — and whether the distinction matters for tomato spotted wilt virus management.

Episode summary generated using claude.ai