WINETECH Technical Yearbook 2021

Basal end

% Reduction

Product 1

FIGURE 1. Application of dry product formulation to dampened basal ends of callused graftlings before planting.

D pathogens

2016/17 2017/18

1,5 b

76,9230769

Basal end Roots

10 15 20 25 30 35 40 45 50

4,5 BC

40

0 10 20 30 40 50 60 70 80 90

Dry product

3,13 9,22

2016/17 2017/18

50,4 16,4

32,53

Product 2

4,53

2016/17 2017/18

1 b

84,6153846 46,6666667

Dry product + drenches

4 BC

1,38 3,44

2016/17 2017/18

39,2

26,4

28

15,73

Product 3

2016/17 2017/18

1,5 b

76,9230769 33,3333333

Fungal incidence (%)

Trichoderma incidence (%)

30min HWT + dry product

0 5

5 BC

18,63 15,56

2016/17 2017/18

30,8 20,4

20 12

2017/18 Product 4

2016/17 Dry product

2017/18

2016/17 Dry product + drenches

2016/17 30min HWT + dry product 2017/18

2016/17 Monthly drenches 2016/17 2017/18

2016/17 Soaking

2017/18

2016/17 Untreated control 2017/18

1 b

84,6153846 -46,666667

2016/17 Xylem

2017/18

2016/17 Pith

2017/18 Monthly drenches

2016/17 Root attachments 2017/18

2016/17 Central roots

2017/18

2016/17

2017/18

Root tips

2017/18

11 A

14 16,67

2016/17

19,2

8,8

Trichoderma BFD pathogens FIGURE 2. Incidence of Trichoderma and BFD pathogens in different tissue types following treatments with Trichoderma-based products. The xylem and pith tissues were from rootstock bases. 2017/18 9,6 7,47 FIGURE 2. Incidence of Trichoderma and BFD pathogens in different tissue types following treatments with Trichoderma -based products. The xylem and pith tissues were from rootstock bases. Soaking

Basal end Roots FIGURE 3. Incidence of Trichoderma in the basal ends and roots of vines following different methods of application of Trichoderma post callusing. Data shown only for treatments that were repeated over two seasons. Product 5 FIGURE 3. Incidence of Trichode ma in the basal ends and roots of vines following different methods of application of Trichoderma post callusing. Data shown only for treatments that were repeated over two seasons. 2 b

2016/17 2017/18

69,2307692

19 28,22

3 BC

60

WINETECH TEGNIES JUL IE 2021 Comparing the different Trichoderma- bas d p oducts that wer evaluated, in both seasons Product 5 resulted in higher Trichoderma re-isolation percentages from the basal ends, though not differing significantly from Product 3 (figure 4). Interestingly, significant differences in the 59 For the trial evaluating different Trichoderma-based products to nursery vines post callusing, treatments included six commercial products, of which two are registered for pruning wound appli­ cation on grapevines, and two isolates that are in the process of commercialisation USPPMT1 and USPPT1 (Stellenbosch University), as well as an untreated control. All treatments were done as described for the dry product application above, except for USPPMT1 that was dipped in Bendazid ® 500 SC instead of water as USPPMT1 is a benzimidazole resistant mutant obtained through gamma irradiation. The root zones of the treated plots were drenched with 10 L of conidial suspension of the respective Trichoderma products at monthly intervals for the first three months after planting. Each treatment consisted of 100 graftlings, replicated four times and repeated over two seasons. Following on site treatment the trials were planted in a com­ mercial grapevine nursery located in the Wellington region and allowed to root for one season according to standard nursery practice. After seven months the vines were uprooted and fungal 2016/17 8,8 2017/18 4 2016/17 6,4 2017/18 2 Basal end Roots 2016/17 38,5 2017/18 29 2016/17 40,5 2017/18 26,5 2016/17 47,5 2017/18 40,5 pathogens. However, BFD is often more sever when occurring together with other grapevine trunk diseases (GTDs) and infec- tions often s em from infecte propagation material. Therefore, minimising infections of other GTDs by me ns of HWT of dor- mant grafting material is advantageous and will aid in cultivating heal hier vines. 2016/17 2017/18 5 1,5

5,87

vii) HWT at 50°C for 45 minutes and soaking for one hour in conidial suspension. callus roots break off during the process, pro- viding di ect infection sites for BFD patho- gens. The protection offered to the exposed basal en s by Trichoder a by means of competition for infection sites and antibiosis cou d aid in controlli g the disease. The HWT of grafting material in combi- nation with the dry product application was done in both seasons and showed that Trichod ma could successfully colonise the hot water treated material, and only resulted in significantly less colonisation in the first season from the dry product treatment. HWT (before planting) did not have an effect in the colonisation of BFD viii) HWT at 50°C for 30 minutes. ix) HWT at 50°C for 45 minutes. x) An untreated control. For the respective treatments that received dry product applica­ tions (i, ii and iii) approximately 30 mm of the basal ends of the rootstock material were dipped in water and then in one kg dry product formulation, while for soaking (v, vi and vii) approxi­ mately 150 mm of the basal ends of the rootstock material were soaked in a Trichoderma conidial suspension for one hour. For treatments receiving soil drenches (ii and iv) the root zones of the respective plots were drenched with 10 L of conidial suspension at monthly intervals for six months after planting. Each treatment consisted of 100 graftlings, replicated five times and repeated over two seasons. Some treatments were adjusted in the second season and were, therefore, not repeated.

120

2,4

Product 1

6 0 incidence of BFD infections were observed within the basal ends following treatments over both seasons, while no significant differences could be observed in the roots, again highlighting the protection offered by Trichoderma in the basal ends. The BFD infections in the basal ends were reduced by between 62% and 85% by the different product treatments in the first season. Although some of the products resulted in lower BFD incidences in the second season (reduction of 33%-67% in five treatments), it was not significantly different from the untreated control (figure 5). From this study we concluded that the suc- 20 40 60 80 100 2017/18 2016/17 2017/18 2016/17 2017/18 Trichoderma incidence (%) incidences determined from 25 vines per replicate. Isolations were made from 1) the xylem and pith in the basal end, and 2) three sections of the roots, namely the rootstock attachment, central part and root tips. Fungal isolates representing any of the BFD pathogens or Trichoderma isolates were grouped and identified Product 6 Product 7 Untreated control

2016/17 cess of Trichoderma species as biocontrol agent under nursery field conditions de- pends not only on its antagonistic activity alone (as assessed by in vitro trials), but a combination of several other factors in- cluding the method of application, as well as ability of the isolate to colonise the spe- cific grapevine cultivar. Successful disease management requires an integrated disease management approach. Trichoderma may offer advantages as part of such a strategy where it can be used as a component with HWT and cultural measures. Other options need to be explor d to lower BFD inoculum in the soil using, for example, biofumigation. 2016/17 6,5 a the basal ends of the rootstocks, while the opposite was true for Trichoderma as demonstrated with the different products trial in Figure 2. This effect was, however, variable over the two years. It appears as if Trichoderma were able to prevent pathogen infec­ tion of the basal ends where its colonisation was higher. 2016/17 2017/18 2,5 b 8,5 AB 2016/17 2017/18 2 b 2,5 C 2016/17

19,33 15,67

Untreated control

61,5384615 -13,333333

5,87 1,33

P oduct 2

23,67

12

69,2307692 66,6666667

Product 3

26,33

22

0 0

2016/17 2017/18 Product 1 Product 2 Product 3 Product 4 Product 5 Product 6 Product 7 Untreated control 2017/18 7,5 ABC 2016/17 2017/18 2017/18 2016/17 2017/18 2017/18 2016/17

Product 4

Basal end Roots

4,67

FIGURE 4. Incidence of Trichoderma in the basal ends and roots of vines following the application of different Trichoderma -based products. Data shown only for treatments that were repeated over two seasons.

Product 5

2016/17 2017/18

58,5 43,5

37,67 20,33

WINETECH TECHNICAL YEARBOOK 2021 | 35

Product 6