Disease forecasting

Strawberry Powdery Mildew Prediction Model

With margins depleting and the cost of fungicide increasing, target your spray application with precision

A new web-based real-time prediction system for strawberry powdery mildew has been developed by the University of Hertfordshire and is accessed via the Agri-tech dashboard.

Uses optimum conditions for humidity and temperature to record and forecast when the disease is likely to develop, and alerts the grower when it is time to spray.

Quotes from Users

"Yes system was very user friendly. Very easy to use and also to enter in data such as when sprays have been applied". 

"I didn’t solely rely on the system this year for all decisions but for the one block that we used it on we didn’t have an issue with mildew in there. Will use more next year."    

"This season, following the Mildew Model I would say, has been our ‘cleanest year’ in terms of Mildew, with no outbreaks at all."



  • SPM module accessible from your secure client login area


  • Data easily accessible to view from your SMART device


  • Easily create disease monitoring zones within your farm


  • Can "talk" to a number of sensor manufacturers - speak to us to find out more


  • Record your fungicide with ease from any device, creating a fungicide application report for your field


  • Enables proactive rather than reactive fungicide applications, ensuring maximum benefit from limited chemistry


  • Average cost benefit in 2018 was £250 / hectare, with no detriment to the crop 

 


Spm Graph July 2019 Fungicide Entry

By using the system the grower is able to use fewer fungicide sprays by targeting with prescision.

  • Saves cost
  • Reduces pesticide residue risk
  • Enables intelligent use of limited chemistry
  • Quick and simple to use


How does it work?

A decision support system (DSS) designed to support the grower for the intelligent use of fungicides, spraying only when conditions are favourable for disease development. The prediction system accumulates the number of hours needed for the fungus to grow from spores to producing the next generation of spores.

How does a disease epidemic build up?

The development of disease epidemic contains three phases (Fig 1 below.):
a. Lag Phase: Spore germination, and fungus growth to spore production. Not enough disease development to be detected by naked eye, though early symptoms (cupping) may be visible. Length of lag phase governed by the number of disease conducive hours1


b. Log Phase: Fungus grows and spreads exponentially (i.e. doubles in each time period) at a speed governed by the number of disease conducive hours; the quicker the disease conducive hours accumulate the faster the fungus grows, and the steeper the line of the exponential phase


c. Stationary Phase: No healthy tissue left to be infected

Figure 1(above): a typical epidemic curve, and also shows how disease levels can be kept to a minimum if spraying using the prediction system.

Figure 2(below): the number of disease conducive hours needed for each cycle of spore production. 

1. Disease conducive hours: the number of hours of correct environmental conditions for a particular fungus to grow. For Podosphaera aphanis (Strawberry powdery mildew) the conditions are temperature >15.5°C and <30°C (15.5°C is the minimum temperature for spore germination, whereas 18°C is the minimum temperature for sporulation; see Fig. 2), with relative humidity (RH) >60%.

2. Full life cycle of strawberry powdery mildew, disease characteristic and controlling strategies are available on the AHDB Factsheet 29/16 ‘Control of strawberry powdery mildew under protection’.

What can the prediction graph tell the Grower?


Figure 3 Prediction graph

The Y-axis of the prediction graph indicates the number of accumulated hours where both parameters are met, the X-axis showing the date. When the ascending green line turns to amber (at 115 hours), this is a warning for the grower to prepare to spray. When the line turns to red (at 125 hours), a fungicide spray is needed. At 144 hours, the fungus can start to reproduce and produce spores, i.e. initiate an epidemic if the grower has NOT sprayed. After spraying, grower enters fungicide details and resets the system, which then starts to accumulate disease conducive hours.


Points to be noted:

  • At the start of the season, always assume there may be some disease, do a clean-up spray;
  • - Low Risk: <50 hours, the fungus will not have grown very much
  • High Risk: >125 hours, the fungus is likely to reproduce and produce spores, fungicide sprays are needed
    - Continuous monitoring of the prediction system is required even when the risk level is low;
  • If there is a constant accumulation (e.g. 24 hours of disease conducive conditions per day), 144 hours will be quickly reached, the grower would need to spray every 6 days; however, this is unlikely. If there is only 6 hours of disease conducive conditions per day, the grower would only need to spray every 24 days;
  • The system is recording disease conducive hours, NOT forecasting disease levels;
  • The grower makes the decision as to what fungicides to use, using Mode of Actions (MoA) in rotation and biological controls if appropriate;
  • Finally, Spray with precision without panicking. Weekly spray (Fig.4-a) is not needed if you follow the prediction system accordingly (Fig.4-b).