With warmer soil temperatures and the start of spring growth, most courses have now begun their cutting season.
But cool nights will mean damage to leaf tips will be slow to heal and will leave plants more susceptible to disease attack.
Watson said: "At this time of year turf managers need to switch to systemic fungicides to avoid the problem of contact only protection being mown off as the leaf grows."
Fusarium Patch and foliar diseases pose the biggest threats at this time of year.
Watson also emphasised the importance of sharp and correctly set mower blades.
He added: "Abrasive effects of worm casts and over winter mud smears can quickly take the edge off recently sharpened blades. The process of lowering cut height with each cut puts extra stress on plants when reserves are low and also exposes a new part of the leaf to infection each time."
He advocates turf managers avoid lowering the height of cut too quickly until growing conditions improve and ensure their Integrated Turf Management plans are designed to minimise stress on the plants, including providing sufficient nutrients and trace elements to stimulate growth.