Addressing the risk of rhizoctonia

As potato planting season approaches, the risk of rhizoctonia solani increases once again. And just like last season, with fewer and fewer seed treatment options, the importance of in-furrow fungicides is clear. What is rhizoctonia? Rhizoctonia solani is a fungus that causes: stem and stolon canker black scurf damping off skin netting tuber growth distortions…

As potato planting season approaches, the risk of rhizoctonia solani increases once again. And just like last season, with fewer and fewer seed treatment options,...

What is rhizoctonia?

Rhizoctonia solani is a fungus that causes:

stem and stolon canker
black scurf
damping off
skin netting
tuber growth distortions

It’s also been associated with higher levels of Internal Rust Spot.

Rhizoctonia can be soil borne and seed borne, with the potential to survive in soil, on volunteer weeds such as nightshade and crop debris. It can also infect many other crops in the rotation.

The fungus can directly impact potato skin quality, establishment and yield.

Geoff Hailstone, UPL’s Potato Crop Specialist, explains:

“Stem canker directly reduces yield and stolon canker affects marketable yield by increasing the fraction of both over and under-size tubers. Seed treatments have historically played a key role, however with the recent loss of both pencycuron and penflufen, disease control continues to be difficult for growers.”

Without these key actives, the only planter seed treatment available is flutolanil. “To mitigate the risk of rhizoctonia then, we need to focus on the value of in-furrow fungicides,” adds Geoff. That’s where ZOXIS and AFFIX come in. Integrated Pest Management (IPM) with in-furrow fungicides Both ZOXIS and AFFIX are broad-spectrum fungicides ideally suited for use in IPM programmes. Applied in the furrow at 3l/ha at planting, they:

Help to reduce the impact of rhizoctonia, providing 750g of azoxystrobin per hectare.
Are effective against all anastomosis groups (AGs)
Consistently reduce levels of Black Dot and Silver Scurf

Use them as part of your IPM strategies to combat the rhizoctonia fungus, as Geoff explains: “Your IPM should include cultural practices such as extended rotations and taking measures which promote early emergence, like planting in warm, well drained seed beds and avoiding deep planting. Clean, certified seed should be the first line of defence.” “The risk of rhizoctonia can also be reduced by managing PCN. Root leachates associated with the nematodes will attract the fungal hyphae and increase infection. At the other end of the season not leaving the crop in the ground longer than necessary at harvest will help.” The loss of key actives used to tackle economically important diseases in potatoes is a continuous threat, as we’ve seen with the recent threat of withdrawal of mancozeb. Growers need a wide variety of options to combat disease and protect their crops through to a successful yield. With rhizoctonia solani, reducing stem and stolon canker, and black scurf, is a challenge, but with the help of in-furrow actives, it is possible. They’ll have an important part to play this season. Find out more about ZOXIS and AFFIX