Potato Late Blight Case Study

Potato Late Blight Case Study

June - Oct 2016 Holland


A Magrow Boom Kit 7000 retrofit kit enabled a reduction in pesticide usage by 25% throughout during field boom spraying applications using a 27m trailed sprayer.


Late blight, caused by Phytophthora infestans, is the most important disease in potato production. Under favourable conditions the pathogen can destroy the potato foliage very rapidly and cause tuber blight. To avoid infection of the foliage, fungicides are frequently sprayed onto the crop. In the Netherlands, in some years up to 15 sprays are necessary to prevent the crop from infection by the pathogen. A field experiment was conducted at the Wageningen University, Lelystad facility to evaluate the performance of the Magrow system vs conventional spraying methods in the efficacy of fungicide spray programs in their control of potato late blight. This paper is a condensed version of the report that was completed by Wageningen University.

Experimental Set-up

The cultivated potato plants (cv Bintje) were grown at PPO Lelystad, the experiment was treated to conform to local good agricultural practice, only the fungicide spraying against P. infestans were carried out as outlined below. The experiment was a randomised and replicated trial.


The fungicides used in the experiment were:

1. Untreated control
2. Conventional 100%
3. MagGrow 100%
4. Conventional 75%
5. MagrowTec 75%


The experiment was artificially inoculated on 23rd June with Phytophthora infestans. These spreader rows were not treated with fungicides during the spraying program in order to increase the likelihood of infection in the trial area. Sprinkler irrigation facilitated the potato late blight epidemic

Disease Observations 

Disease observations were carried out once a week. The Standard Area under Disease Progress Curve (StAUDPC) was calculated which provides an indication for disease development during the growing season. The experiment was harvested on 26th September and tuber blight assessments were made shortly after harvest and after incubation in a non-refrigerated storage. Both the number and weight of the potatoes were assessed.

Disease Assessment Results 

The table below shows the results of the weekly assessments of the percentage infected foliage for each of the treatments and the calculated StAUDPC for each treatment at the completion of the trial.

It can be seen from the data that the MagrowTec treatments displayed less disease pressure compared to the conventional with the MagrowTec 100% reducing the infestation of Phytophthora by17%.

Effect of Spray Techniques on Disease 


 Yield Results 

The yield results are presented below. The results show that the Magrow 100% rate increased the marketable yield by 1.2t compared to the Conventional sprayed with the same fungicide rates, while the MagGrow 75% rate increased marketable yield by 2.3t when compared to its Conventional equivalent.

The data also shows that the Magrow 75% rate produced higher marketable yield of 0.7t when compared to the Conventional 100% and therefore points to conclusion that the MagrowTec system enables the reduction in pesticide by 25% compared to Conventional spraying while maintaining acceptable yield levels, or using 25% less pesticide Magrow achieves same results as conventional at full rate.

he MagrowTec system reduced % tuber blight by 67% compared to Conventional spraying techniques.

Effect of Spray Techniques on Yield (t'ha) and Tuber Blight