Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
42 Cards in this Set
- Front
- Back
|
What are the best diagnostic signs and symptoms of Bermudagrass Decline/ Take-All Root Rot (BD/TRR)? |
Stolons and roots dark (lesions) in color. Foliar symptom: chlorosis form the tip down, Absence of root hairs, darkening of stele and sloughing of root cortex |
|
|
Is BD/TRR pathogen a spore-former or a non-spore-former? |
Spore forming |
|
|
How does the pathogen infect turfgrass plants? What kills plants infected with the BD/TRR pathogen? |
Infects new roots at high temperatures, colonizes root cortex and vascular system |
|
|
What species of turfgrasses are susceptible? (BD/TRR) |
Bermudagrass, St. Augustinegrass, centipedegrass |
|
|
What effects do nutrients such as N, P & K have on the disease? (BD/TRR) |
Promotes optimum root growth |
|
|
What environmental conditions are required for BD/TRR to develop? |
>85F, wet conditions, mid summer-early fall, most severe when mowing height is low, pH is high, thatch is thick, and bad compaction |
|
|
What species of turfgrass are resistant or immune to BD/TRR? |
No bermudagrass cultivars, Zoysiagrass somewhat resistant |
|
|
What turf nutrients suppress BD/TRR? |
N,P,K, Mn, Zn |
|
|
In what ways can the environment and turfgrass be manipulated to suppress BD/TRR? |
Decrease shade, increase air circulation, reduce pH, thin thatch |
|
|
Name a fungicide that will control BD/TRR? |
Heritage, T-Storm |
|
|
During what season(s) are preventive applications of BD/TRR fungicides applied in GA? |
Begin applications about 3-4 wks after spring green-up. Continue at 3-4 wk intervals. |
|
|
Is summer patch spore forming? |
yes |
|
|
which turf species are susceptible to summer patch? |
Kentucky Bluegrass, fine fescues, creeping bent grass |
|
|
What are the distinct diagnosis symptoms of summer patch? |
Dark brown to black roots, hyphae on root surface, foliar symptoms: leave turns yellow from tip downward |
|
|
Environmental conditions that favor summer patch? |
turf that is heat stressed, near roads or sidewalks, |
|
|
Resistant species to summer patch? |
All warm season grasses, ryegrass, tall fescue |
|
|
Cultural control methods for summer patch? |
Increase mowing, reduce thatch, increase aeration, irrigate longer and less frequently, apply N in fall and early winter for root development, use ammonium sulfate as nitrogen source to drop pH |
|
|
What are chemical controls for summer patch? |
azoxystrobin, fenarimol, triadimefon, thiophanate-methyl, Prevention spray starts in May |
|
|
Distinct diagnosis symptoms for Fairy ring? |
Thick layer of mycelium between thatch and soil, Mycellial strands present at bottom of thatch layer, puff ball fruiting structures (type 3) |
|
|
Chemical management for fairy ring? |
Soil sterilization with methyl bromide, fungicide application of bayleton, heritage, prostar, triadimefon |
|
|
Cultural methods of managing fairy ring? |
three options -drench fairy ring with water 4-6 weeks
-Remove infected soil and replace with new soil
-Remove infected sod, mix with various fairy ring mycelium to have antagonism and replant |
|
|
Resistant cultivars for fairy ring? |
none |
|
|
Symptoms of type 1 fairy ring/ killing ring? |
Bare arcs or rings ranging from inches to feet across, Dark green grass surrounding dead zone caused by fairy ring |
|
|
Symptoms of type 2 fairy ring/stimulated ring? |
dark green/black rings, stimulated turf, can turn into type 1 rings |
|
|
Symptoms of type 3 fairy ring. ring of mushrooms? |
Fruiting puff ball structure present above ground in a circle or arc |
|
|
What environmental conditions favor fairy ring? |
Soils high in OM, abundant soil moisture in spring and fall followed by dry period in summer |
|
|
Susceptible species of grasses to fairy ring? |
all warm and cool season grasses |
|
|
Chemical control of Pythium root rot/dysfunction? |
contact-koban, segway
localized- insignia
|
|
|
susceptible species for pythium root rot? |
All turf grasses, cool season more susceptible (creeping bentgrass) |
|
|
Cultural methods to manage pythium root rot? |
control nematodes, avoid high N application in spring, improve aeration, decrease shade |
|
|
Key diagnostic symptoms for pythium root rot? |
Root tip stunting and degradation , no discoloration, thinning, irregular pattern, leaf die back from tip down |
|
|
Favorable conditions for pythium root rot? |
High water content in root zone, low oxygen, wide range of suitable temperatures |
|
|
Is pythium root rot spore forming? what spores are present? |
Yes, oospores in dead tissue, thatch, or soil to overwinter.
Sporangia contain swimming zoospores
Hyphae or zoospores inoculate |
|
|
Symptoms of nematodes? |
irregular to round patches, chlorosis, yellowing, decline in growth, turf thinning, other infections, shallow root systems |
|
|
Environmental conditions favorable for nematodes |
hot weather, drought, stressed, low fertile turf |
|
|
Ways nematodes spread |
moved by machinery, water, wind, transplants, people |
|
|
Sting nematodes |
most widespread, destructive, introduced by infected sod, damage sandy soils, attach young plants, reproduce sexually |
|
|
Lance nematodes |
threshold level: 100 per soil sample |
|
|
Ring nematode |
Threshold: 500 in St. Augustine, 150 in Centipede |
|
|
Controlling nematodes |
soil test, avoidance (planting non infected plant material), maintain optimal fertility (reduce succulent root growth), deep non frequent irrigation, compaction and aeration-tolerance |
|
|
susceptible species of turf to nematodes |
Ring nematode- centipede grass Cyst-St. Augustine
No nematicides available |
|
|
Modern nematicides |
nortica, econem, multiguard protect, avid |
