Apparatus for detecting climatic conditions favoring the development of Peronosporales

Apparatus for detecting climatic conditions favourable to the development of Peronosporales on plant leaves and for indicating the optimum time for effecting fungicidal treatment thereof, said apparatus comprising:

• sensor means for detecting conditions corresponding to a saturation or superficial dampness of plant leaves sufficient to allow the development of zoospores;
• timer means connected to the sensor means and operative to output an `infestation` signal indicative of the occurrence of a Peronosporales infestation if the said conditions of saturation or of surface dampness of the leaves persist for a time period sufficient for the penetration of the zoospores into the stomata of the leaves, said timer means being so arranged that the duration of the time period timed thereby is a function of the ambient temperature;
• auxiliary timing means operatively interconnected with said timer means and responsive to the generation of a said infestation signal to time a delay period during which the output of a further infestation signal is prevented, the timer means at the end of said delay period being arranged to be in a state ready to repeat its timing function for a further Peronosporales infestation;
• and
• monitoring means responsive to each said infestation signal to monitor the speed of advance of the Peronosporales infestation indicated thereby as a function of the temperature and the humidity of the air, said monitoring means comprising a temperature sensor operative to provide an output signal indicative of the ambient air temperature, a humidity sensor operative to provide an indication of the ambient humidity, a pulsed signal generator connected to said temperature and humidity sensors and operative to generate a pulsed electrical signal the frequency of which is dependent on the ambient temperature and humidity, a plurality of monitor counters, control means responsive to successively generated said infestation signals from said timer means to cause successive ones of said monitor counters to start counting the pulses produced at the output of the said pulsed signal generator, the counts of each counting monitor counter being indicative of the advance of a corresponding infestation detected by the apparatus, and output and display means operable to provide a visual indication of the current counts of said monitor counters.