Sclerotia hold in the ground five years or more, so a crop rotation can run its course and the disease still returns. Bikash Ghimire’s answer for southern blight is a shovel: dig the plant out, turn the soil eight centimeters deep, and bury the sclerotia where they cannot surface.
Ghimire is the new ornamental pathologist in the University of Georgia Department of Plant Pathology, and he sorts cut flower disease by where the crop grows before he sorts it by pathogen. A high tunnel hands back irrigation control, a longer season, and longer stems, and charges for it in reduced airflow, humidity, and heat stress. Same crop, different disease.
Fungicides come last in his order of operations. Certified organic growers work with biologicals and plant extracts, and those are preventive only, so the cultural side carries the load: resistant cultivars, sanitation, roguing, early scouting, crop rotation, irrigation, and fertility.
He then walks eleven diseases in about twenty minutes. Root and crown rot, and why water molds releasing motile zoospores make overwatering the predictor. White mold (Sclerotinia sclerotiorum) in cool wet conditions against southern blight (Agroathelia rolfsii, formerly Sclerotium rolfsii) in Georgia summer heat. Fusarium stem rot in lisianthus. Botrytis in the standing plant and again in the cooler. Powdery mildew, downy mildew, snapdragon rust, Cercospora leaf spot in zinnia, and angular bacterial leaf spot.
For viruses he shows an Agdia ImmunoStrip: macerate a leaf, drop it in the buffer bag, read two lines or one in five minutes, at six to eight dollars a strip.
Recorded July 23, 2026 at the second annual Cut Flower Symposium, hosted by the UGA Center for Urban Agriculture with the Georgia Green Industry Association. Segment 8 of 8. CEU Categories: [PENDING].
Chapters
0:00 Introduction and Bethany Harris
0:27 Ghimire’s Opening and Background
0:49 Open Field Production and Weather
1:19 High Tunnel Production: Pros and Cons
1:54 Soil, Previous Crop, and Survival Structures
2:29 Raised Beds and Organic Amendments
2:53 Organic Versus Conventional Fungicide Options
3:24 Why Cultural Practice Comes First
4:16 Root and Stem Diseases Versus Foliar Diseases
5:08 Where the Pathogens Come From
6:34 Root and Crown Rot: Reading the Symptoms
7:26 Water Molds, Sporangia, and Zoospores
8:10 Managing Phytophthora: Water and Drainage
9:06 White Mold, Sclerotinia sclerotiorum
10:21 Sclerotia and Five Years in the Soil
11:02 Southern Blight, Agroathelia rolfsii
11:47 Burying Sclerotia and Preventive Fungicides
12:52 Fusarium Stem Rot in Lisianthus
13:36 Botrytis: Gray Mold in Field and Storage
15:16 Botrytis Management: Deadheading and Spacing
15:54 Powdery Mildew and Host Specificity
16:31 FRAC Groups, DMI, QoI, and MilStop
16:54 Downy Mildew
17:28 Leaf Rust in Snapdragon
18:34 Fungal Leaf Spot: Cercospora in Zinnia
19:01 Leaf Spot Management and Irrigation
20:02 Bacterial Leaf Spot: Angular Lesions and Halos
21:10 Virus Diseases and Their Insect Vectors
22:23 ImmunoStrips: Five Minute Field Testing
23:42 Biological Control Products
24:16 Resources: e-GRO and the Pest Management Handbook
25:02 Q&A: Aster Yellows in Coneflower
26:13 Q&A: Botrytis in Tulips, Year to Year
27:46 Q&A: Bacterial Stem Rot and Pectobacterium
Questions Answered
My plants are yellowing and wilting in patches. Root disease or stress? Pull the whole plant, roots included. Above ground the two look alike. Below ground a root disease shows reddening or discoloration, the roots go soft and slough off, and there is a bad odor.
Which fungicide groups did he name? FRAC code 3, DMI, QoI with azoxystrobin in group 11, some group 7 materials, and MilStop as a biorational for powdery mildew. For Botrytis, a contact first, chlorothalonil or fludioxonil, then a systemic, tebuconazole, azoxystrobin, or boscalid.
Aster yellows in coneflower, first time. What now? Uproot and dispose of the plant safely. It is caused by a phytoplasma and gets confused with herbicide injury because of the witches’ broom symptom. He believes hoppers transmit it and adds insecticide against the vector.
Botrytis went through my tulips. Will it be waiting next spring? Yes, and not necessarily in the soil. The conidia survive in plant debris and return if you plant the same host. Scout early, then apply a contact fungicide at the start of the season if you are replanting the same bed.
Resources
- e-GRO, an online platform covering disease, insect, and nutritional disorders. He points at a link on a slide. No address is spoken.
- Georgia Pest Management Handbook, for fungicide rates and intervals.
- Agdia ImmunoStrips, also available for TMV, CMV, Xanthomonas, Phytophthora, and Rhizoctonia.
- His contact information is on the closing slide but is not spoken on the recording. It has to be added by hand before publication.
Platform Note (not part of the pasted description)
Length. Everything from the opening line through the Resources block measures 4,888 characters, inside YouTube’s roughly 5,000-character field, with 112 characters of headroom. Segment 03 shipped with 26 and segment 04 with 860. This one sits between them and much closer to segment 03, so re-count after any edit. The first draft came in at 5,603 and took six passes of prose trimming to fit.
All 34 chapter markers are kept, costing 1,460 characters, which is 30 percent of the description. Each was verified by script against a block start time in the corrected transcript at Stage 2. Cutting chapters was the obvious lever and it is the wrong one here: the segment is a disease-by-disease walk, and a grower who came for southern blight wants to land on 11:02 rather than read a paragraph.
Eight of the twelve Q&A pairs were cut. Four carry over. What went, and why:
| Cut pair | Reason |
|---|---|
| High tunnel against open field | The tradeoff is in the lede at a third the length. |
| What organic growers have to work with | The preventive-only constraint is in the lede. |
| Where the pathogen comes from | Six routes, none of which compress. Full version is on the website. |
| Why overwatering keeps coming up | The zoospore mechanism is in the lede. |
| Sclerotia once they are in the ground | The shovel answer opens the description. |
| White mold against southern blight | The temperature split is in the lede with both binomials. |
| Keeping Botrytis out of harvested stems | Storage is named in the lede; the spacing detail is on the website. |
| Confirming a virus without sending a sample | The ImmunoStrip walkthrough is in the lede with the price. |
All twelve pairs are on the website version. The four kept here are the diagnostic question a grower searches for, the fungicide group list, and both audience questions, which are the parts with no counterpart anywhere else in the file.
Two addresses are missing because neither was spoken. The e-GRO link at 24:32 and his contact slide at 25:01 are both pointed at and never read. Same shape as segment 03’s QR code and segment 04’s email. Both block publication.
No content rests on either open flag. Block 85’s [VERIFY: "copseps"] sits inside the sporangia sentence and block 182’s [VERIFY: "bacia"] is the second downy mildew host. The lede describes sporangia and zoospores without the flagged descriptor, and the downy mildew chapter names no host.
Timestamp format is M:SS and MM:SS throughout, since the segment runs under an hour.
Scaling Note
Target. Stage 3 derives from the Stage 2 package and scales with it. Segment 04’s YouTube file ran 8.2 KB against a 15.0 KB archive summary, a ratio of 0.55. This archive summary is 14.8 KB, so the proportional target was about 8.1 KB.
Delivered. 8.2 KB, of which the pasted description is 4,888 characters. The talk runs eight minutes longer than segment 04’s with fourteen more chapters, and the description still fits, because the Q&A cut ran deeper: four pairs kept out of twelve, against segment 04’s four out of twelve at a shorter chapter list. The watch item predicting segment 03’s pressure at this runtime was right, and cutting the Q&A before writing rather than after counting is what kept it inside.
What was not scaled. The chapter list and the Platform Note’s cut-pair table, which are what a person editing this file later needs.
Processed for UGA Center for Urban Agriculture / Cut Flower Symposium Archives
Source: Stage 2 Archive Package, GTBOP_Archive_Summary_2026-07-23_GhimireDiseaseManagement.md