Source webinar: Cut Flower Symposium, segment 08 of 08, July 23, 2026
Speaker: Bikash Ghimire, Ornamental Pathologist, Department of Plant Pathology, University of Georgia
Duration: 28:31
CEU Categories: [PENDING]
Prompts: 11, covering 0:00 to 28:31 with no gaps
Scope Notes
No prompt asks a student to report the second downy mildew host. Prompt 7 covers downy mildew by its diagnostic sign and its systemic movement, because the host name after sunflower is unintelligible in the recording and a student would be listening for something that is not there.
No prompt asks for a product class for bacterial disease. Prompt 8 covers the fungal against bacterial distinction on lesion shape, which is the part the speaker gets right and the part that changes what a grower does next. His product recommendation there calls mancozeb a copper, and building a review task on it would have students memorising the error.
Prompt 5’s key points avoid the sporangia descriptor at 7:26 that no transcription pass recovered, and rest on the zoospore mechanism he states clearly on both sides of it.
Review Task 1
Watch: 0:00 – 2:53
Task: Compare the two production environments the speaker describes and list what each one costs and what each one buys.
Key Points to Identify:
- Open field is weather dependent: drought, rain, storm, wind, temperature extremes, and rainfall you cannot control
- High tunnel gives reduced airflow, high humidity, and heat stress, but returns irrigation control, extended seasons, and longer plants with thicker stems
- The same crop can get one disease in one environment and a different one in the other
Review Task 2
Watch: 2:53 – 4:16
Task: Write down the speaker’s order of operations for disease management and explain why he puts fungicides last.
Key Points to Identify:
- Certified organic growers have fewer chemical options and work with biological agents or plant extracts
- Biological products have no curative activity, so they only work applied preventively
- Cultural practice comes first: resistant cultivars, sanitation, roguing, early scouting, crop rotation, irrigation and fertility management, with fungicide at a minimum dose and rate if it is needed at all
Review Task 3
Watch: 4:16 – 6:34
Task: List the routes by which a pathogen enters an operation, and note which of them a grower controls directly.
Key Points to Identify:
- Infested seed, named specifically for downy mildew and bacterial leaf spot
- Incoming plants that are asymptomatic on arrival, and contaminated trays, pots, tools, pruning equipment, and benches
- Crop residue from previous seasons, plus wind-blown and rain-driven spores, which is the route no grower controls
Review Task 4
Watch: 6:34 – 7:26
Task: Describe how the speaker separates a root disease from abiotic stress in the field.
Key Points to Identify:
- Above ground both produce patches of chlorotic, yellowing, wilting plants, which is why the symptom alone is not enough
- The whole plant has to come out of the ground with the root system intact
- The root shows reddening or other discoloration, and the problem is in the root and crown region
Review Task 5
Watch: 7:26 – 9:06
Task: Explain the term water mold and connect it to the irrigation advice the speaker gives.
Key Points to Identify:
- The pathogen produces sporangia, and the zoospores inside them are motile and need free water to move
- Given standing water they swim to a healthy root system and infect it, which is why overwatering and poor drainage predict the disease
- Management follows the mechanism: water management, drainage, incorporating organic material, and removing infected plants whole
Review Task 6
Watch: 9:06 – 12:52
Task: Contrast white mold and southern blight on the two axes the speaker uses, and record what he says about sclerotia.
Key Points to Identify:
- White mold (Sclerotinia sclerotiorum) favors cool conditions; southern blight (Agroathelia rolfsii, formerly Sclerotium rolfsii) favors warm, with humidity and moisture much the same for both
- Sclerotia are pigmented overwintering structures reported to survive five years or more, which is why rotation alone may not clear a bed
- His physical control for southern blight is to dig, remove, turn the soil about eight centimeters deep, and bury the sclerotia, and never to compost infected plants
Review Task 7
Watch: 12:52 – 17:28
Task: Track Botrytis from the standing crop to the cooler, and note where powdery and downy mildew differ in where you look for them.
Key Points to Identify:
- Botrytis colonizes succulent tissue, flowers and young shoots, and is a post-harvest and storage problem as much as a field one, with spores windblown above 85 percent humidity or splashed by irrigation and rain
- Management is removing infected plants and deadheaded stems, air circulation, and spacing so humidity does not sit on the leaf surface
- Powdery mildew shows as a powdery mass on the upper leaf surface and is host specific by pathogen species; downy mildew shows white spore production on the underside and moves systemically through the vascular region
Review Task 8
Watch: 17:28 – 21:10
Task: Note how the speaker tells fungal leaf spot from bacterial leaf spot, and why the distinction changes what a grower does.
Key Points to Identify:
- Rust shows yellowish patchiness above and spore-filled pustules below, and rust spores travel kilometers on wind; some rusts need two hosts, but the sunflower and snapdragon rusts need only one
- Cercospora leaf spot in zinnia shows a tan center inside a purple margin, favored by leaf wetness, high humidity, and poor air circulation, and the fungus overwinters in plant residue
- Bacterial leaf spot is angular and follows the leaf veins with a yellow halo, where fungal spots form concentric rings; bacterial pathogens are seed-borne, so seed must not be saved from infected plants
Review Task 9
Watch: 21:10 – 23:42
Task: Summarize what the speaker says can and cannot be done about a virus, and describe the field test he demonstrates.
Key Points to Identify:
- INSV in snapdragon and TSWV in zinnia are his examples; vectors are thrips, aphids, and mites, and spread also happens by grafting and propagation
- There is no cure: uproot the plant, dispose of it safely, control the vector with insecticide, and do not propagate infected stock
- Agdia ImmunoStrips read in about five minutes, two lines positive and one negative, at six to eight dollars per strip, with strips also available for TMV, CMV, Xanthomonas, Phytophthora, and Rhizoctonia
Review Task 10
Watch: 23:42 – 25:02
Task: List the biological materials the speaker names and record the caveat he attaches to the list.
Key Points to Identify:
- Bacillus products for a range of foliar diseases and root and crown rot; Trichoderma for Fusarium, Pythium, Phytophthora, and root and crown rot; plus neem oil, Pseudomonas, and plant extracts
- The list he shows is labeled for the edible greenhouse, and he says it can be applied to ornamentals
- His own testing is in turfgrass and the ornamental work is ahead of him, which is a statement about where the local data stands
Review Task 11
Watch: 25:02 – 28:31
Task: Work through the three audience questions and note the management step each answer turns on.
Key Points to Identify:
- Aster yellows is caused by a phytoplasma, is confused with herbicide injury because of the witches’ broom symptom, and is handled by uprooting and safe disposal plus vector control; he says he believes hoppers transmit it and does not recall which
- Botrytis returns from conidia surviving in plant debris rather than requiring soil, so the tulip grower scouts early and treats at the start of the season if replanting the same bed
- His sequence is a contact fungicide first, chlorothalonil or fludioxonil, then a systemic, tebuconazole, azoxystrobin, or boscalid, depending on how severe the symptoms get
Coverage Check
| Prompt | Range | Minutes |
|---|---|---|
| 1 | 0:00 – 2:53 | 2.9 |
| 2 | 2:53 – 4:16 | 1.4 |
| 3 | 4:16 – 6:34 | 2.3 |
| 4 | 6:34 – 7:26 | 0.9 |
| 5 | 7:26 – 9:06 | 1.7 |
| 6 | 9:06 – 12:52 | 3.8 |
| 7 | 12:52 – 17:28 | 4.6 |
| 8 | 17:28 – 21:10 | 3.7 |
| 9 | 21:10 – 23:42 | 2.5 |
| 10 | 23:42 – 25:02 | 1.3 |
| 11 | 25:02 – 28:31 | 3.5 |
Eleven contiguous ranges, no gaps and no overlaps, ending at the last frame. The set doubles as a Moodle course outline: prompts 1 to 3 are the framing unit, 4 to 6 the soilborne unit, 7 to 8 the foliar unit, 9 to 10 the diagnostics and biologicals unit, and 11 the audience questions, which stand alone as a short clip.
Prompt 4 is the shortest at 52 seconds and is kept separate on purpose. Telling a root disease from stress is one discrete skill, and folding it into the water mold prompt would bury the only diagnostic step in the segment a grower can do with their hands.
Processed for UGA Center for Urban Agriculture / Cut Flower Symposium Archives
Sources: Corrected SRT (Stage 1), GTBOP_Transcript_2026-07-23_GhimireDiseaseManagement.srt (315 blocks); Archive Package (Stage 2), GTBOP_Archive_Summary_2026-07-23_GhimireDiseaseManagement.md