WINETECH Technical Yearbook 2020

TABLE 1. The number of isolates and identity of Eutypa-like species isolated from dying spurs, grapevine wood showing wedge-shaped necrosis and fruiting bodies (perithecia).

close proximity to vineyards. Dead wood attached to trellis wires is a significant source of inoculum. When removed, the wood must immediately be destroyed. If the wood is chipped, it must be done as fine as possible and preferably composted. However, the most important control measure is the protection of pruning wounds with fungicides and/or biological control agents. These treatments must be applied as soon as possible after pruning, but in the case of sapflow, the optimum time is six hours after pruning. The occurrence of Eutypa-like species in dying spurs of plants as young as four years clearly highlights the fact that pruning wound protection must start when the first wounds are made in new vineyards. SUMMARY Eutypa lata and six other Eutypa-like spe- cies were isolated from grapevines. Five of these, namely Cryptovalsa rabenhorstii , Eutypa consobrina , Eutypella citrico- la , Eutypella microtheca and a new spe- cies, Eutypa cremea , were isolated for the

first time from South African grapevines. These species, together with eight other Eutypa-like species recently isolated from other woody hosts in close proximity to vineyards, were subjected to pathogenicity studies. All 15 species, whether originating from grapevine or non-grapevine hosts, were able to infect, colonise and cause lesions on grapevine. Eutypa lata and se­ veral Eutypa-like species were identified as grapevine pathogens and should be taken into consideration in integrated manage- ment strategies, based on sanitation and pruning wound protection practices, to ensure sustainable grapevine production in South Africa.

Number of isolates Dying spurs Wedge-shaped necrosis Perithecia

Eutypa-like species

76

2 0 0 3

69

Cryptovalsa ampelina Cryptovalsa rabenhorstii

1 1 7

0 0

Eutypa consobrina

11 92

Eutypa cremea

33 44

190

Eutypa lata

18

7 2

Eutypella citricola Eutypella microtheca

2

0

dimension to the epidemiology of these pathogens. Very little is known about the infection of green and lignified shoots

production in South Africa. The fact that Eutypa-like isolates collected from non-grapevine hosts are pathogenic to grapevine, further highlights this point. Management practices should include sanitation practices to reduce inoculum sources within and around vineyards. Such practices include the removal of dead wood in vineyards and surrounding fruit orchards, but also in other woody hosts in

during the season. CONCLUSION

For more information, contact Lizel Mostert at lmost@sun.ac.za or Francois Halleen at halleenf@arc.agric.za.

Eutypa lata and several Eutypa-like species were identified as grapevine pathogens and should be taken into consideration in integrated management strategies to ensure sustainable grapevine

WINETECH TECHNICAL YEARBOOK 2020 76