International Journal of Tropical Insect Science

, Volume 39, Issue 3, pp 219–227 | Cite as

Effect of broad-spectrum insecticide applications on insect pest damage and nut mass of pecan, Carya illinoinensis (Juglandaceae), in the Vaalharts production region of South Africa

  • J. L. HattingEmail author
  • F. J. Calitz
  • H. Du Toit
  • B. Germishuizen
Original Research Article


Pecan, Carya illinoinensis (Juglandaceae), cultivation is one of the most rapidly expanding agro-industries in South Africa. A shift in production towards the North central (Vaalharts) region has evoked new interest in the insect pests and their potential damage-causing status. Surveys were conducted at three sites from October 2013 to June 2017 to identify the pestiferous and beneficial insect species, while concurrently (2015/16 and 2016/17 seasons), measuring the effect of 1 – 4x insecticide applications on nut mass and damage. The most prevalent pests represented five families, comprising of stinkbugs (Pentatomidae), snout weevils (Curculionidae), aphids (Aphididae), leafhoppers (Cicadellidae) and plant bugs (Miridae). At the highest frequency (4x), mist blower applications of a broad-spectrum insecticide (active: Cyfluthrin) showed no significant increase in nut value, compared with untreated controls at any of the three trial sites (Magogong, Tadcaster and Bull Hill). However, under the more marginal conditions at Bull Hill, the data did suggest a beneficial effect of the water x wind components (water control) on nut-set and development. At this site, the water control resulted in an 18.58% increase in nut value, seemingly linked to the October application in support of pollination/fertilisation; while still allowing overcompensation in response to insect herbivory. With only 2.61% of nuts harvested from controls considered as damaged (insect, physiological or microbe-related) and no significant benefit derived from any of the insecticidal treatments at any site compared to the water control, the perceived negative impact of locally occurring insect pests on nut development appears negligible.


Pecan Carya illinoinensis Insecticide Nut mass Damage Economy 



The authors wish to thank the landowners, Mr. Douglas Craword (Magogong), Mr. Jan Human (Tadcaster) and Mr. Jaco Hamilton (Bull Hill) for making available pecan orchards and for general on-farm assistance during these trials.


This work was funded by the South African Pecan Nut Producers Association (ARC-SG Project number P15000023).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© African Association of Insect Scientists 2019

Authors and Affiliations

  1. 1.Agricultural Research Council-Small GrainBethlehemSouth Africa
  2. 2.Agricultural Research Council-Biometry, Central OfficePretoriaSouth Africa
  3. 3.South African Pecan Nut Producer’s AssociationPaarlSouth Africa

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