Psyllid / Candidatus liberibacter solanacearum (CLso) Research 

The main research programme has been two MPI SFF projects, the second of these (11/058) projects finished in October 2014.

The focus of this research has been on developing insect management programmes which use a combination of forecasting, monitoring and targeted insecticides.


The research to date has shown a good ability to use degree days to predict psyllid epidemics in the Pukekohe region and forecast insecticide intervention and there has been a significant amount of research conducted on a range of spray approaches and developing robust insecticide spray programmes.


The research has also shown sticky traps can be used as an indicator of adults moving into the crop in the Pukekohe region. Positioning sticky traps in the headlands and within the crop could be used to indicate if a headland spray will be adequate to control the pest.


The MPI SFF 11/058 programme also links to other government funded research that has been undertaken to better understand the disease life cycle, insect biology and life cycle and some molecular understanding of the pest.

See below for PDFs of the Psyllid News and Final Research Reports.


Ongoing TPP research includes:


Regional Pest Management Strategies

Psyllid work with continue with trials established in Matamata, Manawatu and Canterbury.  The incidence, importance and timing of pests varies markedly between potato growing regions in New Zealand. The aim of the three field trials is to develop regionally focused pest management strategies, initially focussing on tomato potato psyllid (TPP) and zebra chip disease, putatively caused by Candidatus Liberibacter solanacearum (CLso).

This project will focus on developing reduced insecticide management strategies by: using thresholds to commence a spray programme (psyllid-count based or Degree Days) and incorporation of agricultural oils into a spray programme to protect the crop from insect pests and consequently from being infected with CLso (TPP) or viruses (aphids).

Crop Covers

The Biological Husbandry Unit has undertaken some research on crop covers to exclude the insect pest and have had extremely good results at controlling TPP. The covers also significantly reduced the incidence of late blight so could markedly reduce pesticide application in potatoes. To date the commercial evaluation of the covers and comparison of these to other control methods (forecast and spray or calendar spray) have not been made so the cost benefits cannot be determined. While these covers may not be an option for process potatoes they may have a fit for early generation seed potatoes (they could also exclude aphids and reduce virus risk). Internationally these covers are widely used on brassica crops.

For more information on crop covers in the integrated insect management research project.


Evaluation of Oil Sprays

Research by Peracto has evaluated oil sprays and the use of oils alternated with insecticides and comparisons of different insecticides. The oils, particularly at the higher rate on their own or in conjunction with insecticides, appear to give good levels of control when under low insect pressure.

For more information on evaluation of oil sprays in the integrated insect management research project.


Review of Agrichemical Options

Agrichemical companies have evaluated a number of products in trials.



Evaluation of Tamarixia as a biological control (natural parasitoid of psyllid in Mexico and US) for psyllid in New Zealand. Tamaraxia will not give control in the paddock situation as it only attacks fourth instar larvae but it may suppress overall background population.

For more information on the use of Tamarixia in the integrated insect management research project.


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