9/10/2020 4:09 AM
Good day dear Colleagues,
We've been managing bentgrass sand capped fairways in Moscow for 9 years now. Bentgrass PLS (Putter + L-93 +Southshore) from Jackline Seeds on 10 inches of pure, slightly alkaline sand (pH 7.2-7.4). Generally cold and wet climate. Snow cover for 5 month. Not much thatch (less then 1 inch). Our agronomy program - not more than 50 kgN/ha a year (only liquid), 2-3 light verticutting with topdress, one aeration (hollow coring or solid tinning) with topdress. 40 tons of sand per hectare total. PGR usage based on GDD. LDS is an issue. Spraying WA with Biofungicide (Bacilllus, Trihoderma) - monthly. Almost no synthetic fungicides during growing season (no need), only iron sulfate and phosphites with foliar applications as alternative to organic fungicides. Synthetic fungicides only in pre-winter snow mold preventive program from the end of September till November. Two applications of pendimethalin for control Poa (May, August), one Aceleprine against leatherjacket in August.
First appearance of patches was documented in August 2017 and my first though was - Take All. Soil and tissue analysis on pathogen ID was taken in September 2017. There were numbers of Fusarium species into the thatch/soil upper layer. Kind of "soil borne" diseases. Situation is definitely getting worse year by year. Patches appearance associated with cold, inclement weather (August/September). We've tried to poke a holes in the damaged areas and apply Heritage (Azoxistrobin) with well amount of water but no significant result has been seen.
I would be very thankful for any help, ideas and advices. Thanks in advance.
Take care and stay safe.
Kind regards
Denis