General and introductory

In the previous 32 articles in this series (Parts 1 – 9) the spotlight fell on grapevine abnormalities that may be readily categorised, namely: (i) fungal diseases; (ii) bacterial diseases; (iii) virus and virus-like diseases; (iv) insects and other pests; (v) macro and micro nutrient deficiencies and excesses; (vi) soil chemical and physical problems; (vii) herbicide phytotoxicity; (viii) physiological phenomena; (ix) mechanical damage; (x) graft union problems; (xi) mutations and bud abnormalities; (xii) feeding damage by animals; (xiii) unsound/defective cultivation practices/actions and (xiv) lesser known problem situations. Based on the wide-ranging extent and divergence of abnormality phenomena, it goes without saying that examples representative of the entire spectrum could not be included and that an attempt was made to concentrate on truly characteristic situations.

Apart from harmful interventions caused to the grapevine and its products by proven and visually recognisable phenomena, all grape growing regions in South Africa are familiar with an extensive and widely divergent spectrum of innocuous cases. Ongoing and meticulous monitoring of vineyard blocks is nevertheless strongly recommended, in order to remain abreast of the incidence of such situations, including any associated advantages and disadvantages, even though such scrutiny may be restricted to interesting observations. In this presentation relevant particulars are visually portrayed and elucidated by concise captions.

Miscellaneous

Apart from the possible inclusion of individuals in picking crates during mechanical harvesting, no additional disadvantages associated with the incidence of chameleons could be stipulated (Photo 522). In the case of dragonflies (Photo 523) foliage wires are sometimes used to rest on without causing any damage to grapevines. Although wasps have no harmful characteristics in terms of general cultivation practices, they may cause great frustration among vineyard workers when nests are disturbed and stinging attacks launched in retribution (Photo 524). Similar tendencies apply to honeybees, which sometimes occur in caked format on bunches when the onset of noble rot during dry autumn conditions affects individual berries (Photo 525). Despite the fact that spiders may sometimes look creepy, their presence may have advantages and disadvantages – eating of moths/insects in the former and in the latter, the possibility that they may be crushed as ‘material other than grapes’ (Photos 526 & 527). Apart from proven harmful larvae/caterpillars, strange/unknown examples are often observed on grapevines on a sporadic basis (Photos 528 & 529) – in which case expert advice should be sought at all times to confirm possible harmful interventions that may apply. Although the incidence of birds’ nests (sometimes with chicks) is considered common, there are no real disadvantages, except for possibly being incorporated in picking crates (Photo 530). Unlike feeding damage such as that which may be caused by guinea fowl tucking into grape bunches, thick-knees show no appetite for grapes, despite the fact that chicks are often hatched in the shade of trellised grapevines in separate vineyard rows, whereafter the sites in question are soon vacated (Photo 531). Based on the benefits of mealybug control ascribed to the feeding activities of ladybirds, their presence is strongly encouraged (Photo 532).

Foto522_MAIN

PHOTO 522. Apart from potentially incorporating individuals in picking crates during mechanical harvesting, there are no additional disadvantages associated with the incidence of chameleons.

PHOTO 523. In the case of dragonflies, foliage wires are sometimes used to rest on, without causing any damage to grapevines.
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PHOTO 524. From time to time wasps may cause vineyard workers great frustration, especially where nests are disturbed and stinging attacks launched.
PHOTO 525. Honeybees are occasionally found in caked format on bunches, where noble rot develops in individual berries during late autumn.
PHOTO 526. Although spiders may sometimes look creepy, they have the benefit of eating moths/insects.
PHOTO 527. The possibility that spiders may sometimes be crushed as ‘material other than grapes’, could be a potential disadvantage.
PHOTO 528. In instances where strange/unknown larvae/caterpillars may occur, it is strongly recommended that expert advice be sought, to confirm possibly harmful interventions.
PHOTO 529. Similar to the situation in Photo 528, the utmost care should be taken should any possible feeding damage occur.
PHOTO 530. Although birds’ nests (sometimes with chicks) may be found among trellised grapevines, there is no real disadvantage except that they may possibly end up in the picking crates.
PHOTO 531. An example where the thick-knee parents and their chicks leave a vineyard site.
PHOTO 532. Based on the advantages of mealy bug control by the feeding activities of ladybirds, their presence is strongly recommended.
PHOTO 533. The incidence of harmless pearl glands on young, actively growing organs is a common phenomenon – especially during hot, humid conditions. Not to be confused with guttation or mite eggs.
PHOTO 534. A typical example where tendrils have the tendency to catch, bend over and strangle their own shoot tips.
PHOTO 535. Similar to the situation in Photo 534, tendril associated strangulation affects this young shoot.
PHOTO 536. A further example of severe strangulation effects that may be caused by tendrils, thereby contributing to phenomena whereby normal sap flow may be compromised.
PHOTO 537. Yellowing of shaded leaves can/may occur in dense canopies. PHOTO 538. Although the exudation of bleeding sap is considered common in fresh pruning wounds, in due course this may be converted into sticky, jelly-like, hanging exudations; these may end up as media favourable to harmful fungal growth (09:00 position).
PHOTO 539. A typical example of severely delayed bud burst was observed in these Pinot noir grapevines in Simondium on 30 October 1987.
PHOTO 540. Harmful interventions on this Bukettraube leaf, as a result of overdosing (excessively high concentration) with a specific fungicide applied to prevent oidium.
PHOTO 541. In exceptional cases bunches grow from trunks and/or cordon arms. Despite the absence of shoots and leaves, or even parts thereof, colouration occurred in this Cabernet Sauvignon bunch and it even underwent some degree of ripening.

 

In addition to situations associated with the specific examples mentioned in the previous paragraph, several other examples relative to grapevines may be mentioned, to be respectively classified as either harmful, harmless, or merely interesting. Although widely divergent, some characteristic examples in this regard are highlighted, namely: (i) pearl glands (Photo 533); (ii) strangulation effects by tendrils (Photos 534 – 536); (iii) leaf yellowing in dense canopies (Photo 537); (iv) exudation of bleeding sap (Photo 538); (v) delayed bud burst (Photo 539); (vi) fungicide overdose (Photo 540) and (vii) bunches on trunks/cordon arms (Photo 541).

Conclusion

With the publication of Part 10, which concludes the series about grapevine abnormalities, it is hoped that the compilation lives up to its objectives, namely to capture detailed particulars, both visually and in popular scientific terms, of characteristic abnormality phenomena as these can/may occur across an umbrella spectrum in South African vineyards.

Acknowledgements

A particular word of thanks to Jan Booysen, technical advisor, for accepting the project for publication as a series in Wynboer/Winetech Tegnies, as well as to Anel Andrag, Winetech manager, for her comprehensive input in making this series a reality. Sincere thanks is herewith expressed.

Photography

Photos by Piet Goussard (US), except for examples kindly provided by the following persons/instances. In this regard a special word of thanks to: Erna Blancquaert (Photos 453 & 541); Henning Burger (4, 5, 389, 390 & 430 – 432); Zelmari Coetzee (251 – 253 & 257 – 260); Jeff Joubert (261, 262, 267, 273 & 354); G. Kasdorf, ARC-NIPB (165 & 179); Chris Keet (386); Tanya Lerm (87); ARC Infruitec-Nietvoorbij (7 – 9, 68, 72, 82, 83, 118, 130, 134 – 136, 283, 285, 371, 372, 418, 433, 436, 437, 444, 446, 468, 475, 476 & 481); Pieter Quixley (423 – 428); Pieter Raath (359 & 360); Etienne Terblanche (507); Vititec (242 – 248) and Johann Wiid (167, 169, 263, 265, 266, 270 & 271).

Piet Goussard

Department of Viticulture & Oenology,

Stellenbosch University

For further information contact Piet Goussard at pgg@sun.ac.za.

 

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