Carrot growers should stay on top of foliar diseases right up until harvest, says ProCam agronomist John Cairns.
Fungicides that boast a short harvest interval are useful in ensuring crop yield and quality aren’t jeopardised in the final weeks of the season, says Mr Cairns, who recommends fungicides with multiple actives and modes of action.
“With weather patterns becoming increasingly variable and difficult to predict, carrot growers must ensure their crops remain protected against foliar diseases such as alternaria, sclerotinia and powdery mildew until as close to harvest as possible.”
All three of these diseases have the potential to reduce yield and affect quality in the final few weeks prior to harvest, says Mr Cairns. Good field hygiene, disease tolerant varieties and a long rotation can prevent diseases spreading from one crop to the next.
Alternaria can spread rapidly if warm, wet conditions prevail, while powdery mildew will be the dominant threat in dry conditions. Meanwhile, sclerotinia tends to occur when carrots have filled up and start to drop their leaves onto damp soils.
In addition to using integrated crop protection measures, Mr Cairns says growers should also use suitable fungicide treatments to prevent diseases taking hold – including during the final weeks of growth.
“With a good armoury of fungicides available for carrots it’s not too difficult to find products to target most key diseases, with the period prior to the canopy covering over key to successful control,” adds Mr Cairns.
“Unfortunately, things can get a little trickier as the harvest season approaches, not least because a lot of fungicides have a pre-harvest interval of up to three weeks which means crops can be left susceptible to new infections nearer to harvest.”
Even at this late stage in proceedings, new infections can still have a significant impact on crop yield and quality so it is vital to remain vigilant right until the last moments of the crop’s development.