Crop tour potato - week 26
Fight against phytophthora in full swing
Due to the wet weather conditions, it is important to be careful with phytophthora. The potato growers participating in the Boerenbusiness Crops are therefore busy protecting their plots against potato blight. What strategy do they use in the fight against phytophthora?
The wet weather conditions, in combination with the fast-growing but vulnerable crop, are ideal for phytophthora. The rain and wind also do not make it any easier for potato growers, who are not often able to protect their potato plots under good spraying conditions this year.
Humidity
A strict spraying schedule is of great importance under these circumstances, as Phytophthora can easily strike at a leaf wetting period of 4 to 8 hours with a relative humidity of 95%+. Over the past few nights, these conditions have been present for a long time, according to Sencrop's weather stations (see table below). The potato growers spray with various agents, sometimes also against the Colorado potato beetle and want to prevent phytophthora.
| Date | Humidity | Min. | Max. |
| June 27 | 82.7% | 47.2% | 96.2% |
| June 28 | 89.5% | 78.6% | 97.1% |
| June 29 | 92% | 85.6% | 98.1% |
| June 30 | 91.5% | 86.8% | 94.9% |
| July 1 | 87.8% | 84.8% | 92% |
sprays
Kees Vrolijk, potato grower from Fijnaart (North Brabant), comes out well with his spraying schedule: "Last Wednesday and Thursday I sprayed the potato fields with 0,4 liters of Zorvec + 0,2 liters of Gazelle. on the weather we've had over the past few days, luckily I had sprayed Zorvec, because that now gives me the right to choose a better next spray moment these days. I'm now at 8 days and with this weather it's on the edge. "
A little to the north of the Gewastour plot in Hellevoetsuis (South Holland) it is too wet to spray, potato grower Kees Trouw reports: "It has rained a lot here, but luckily I don't have to spray again until Friday and Saturday. no phytophthora found yet, but I would like to keep it that way. Last round I sprayed 0,6 liters of Revus with 2 liters of Boron and in the coming days I will use Zorvec on the potato fields."
'Being on top of this with this wet weather'
The relatively new product Zorvec has the advantage that it protects 2 to 3 days longer than many other products, so that you have a spraying interval of 10 days under normal spraying conditions. But if the pressure is high and a lot of new leaves are added, then you shouldn't take any risks, says Vrolijk. "As yet I have not encountered anything in the field, but with this weather you have to be on top of it. With this weather you have to go to a lower spraying interval - just like with the other phytophthora agents."
Spraying Dronten, Mill and Sint Hubert and Scharendijke
The other Crop Tour plots were also sprayed with various agents. 0.6 liter Revus + 0.5 liter mantrac + 1 liter bortrac were sprayed on the plot in Dronten. On the plot in Scharendijke, where there has also been prolonged rainfall in recent days, 2 liters of video + 10 kilograms of epso micro top were sprayed. On the plot in Mill en Sint Hubert (North Brabant), 2 liters of Profilux + 0,25 liters of canvas + 5 kilograms of microtop were sprayed.
Jesse Torringa
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