Dusty vineyard roads, spider mites and what growers do about it

What the UC pest guidelines say about road dust

The University of California's Statewide IPM Program publishes pest management guidelines crop by crop. Two of them, both on webspinning spider mites, get specific about roads.

Grapes. The grape guideline says to manage spider mites with a mix of biological, cultural and chemical controls. The first cultural control it lists is putting water or another dust-reducing material on the roads in the vineyard.¹ Then it suggests keeping resident vegetation or other cover in the vineyard middles, where you can, to cut the dust further.¹

Peaches. The peach guideline puts it this way.

"Mite buildups are encouraged by hot, dry, and dusty conditions, so keep orchards well irrigated, and treat orchard roads, if necessary, to keep dust to a minimum."²

On monitoring, it says growers should check every few days if an orchard has problem areas such as trees along roads or water-stressed trees. It also says early-season hot spots are often the dusty or water-stressed parts of the orchard.²

California guidelines, Oregon vineyards

Two things to be straight about before you lean on those lines:

• They're written for California. UC IPM writes for California growers. I quote them because they're specific about road dust, and they aren't Oregon guidance. Your crop adviser is the right person to ask about mites in your block.
• They don't name a product. The grape guideline says "water or other materials formulated to reduce dust."¹ Nothing in either guideline is about lignin sulfonate, and I make no claim that treating a road reduces mites.

What they do show is that growers get told to think about road dust. That part I can help with.

The Rogue and Applegate valleys

Federal wine-region rules draw the lines here. The Rogue Valley viticultural area "is located entirely within Jackson and Josephine Counties in southwestern Oregon."³ The Applegate Valley viticultural area sits entirely inside it, also in Jackson and Josephine counties.⁴

Both counties are where we work, so a vineyard or orchard road anywhere in either valley is one I can come look at. We're based in Medford, and I've been putting down dust control on Southern Oregon roads for more than 20 years.

Treating vineyard and orchard roads

We treat a vineyard or orchard road the same way as any gravel road. We set an appointment, pre-wet it with water, then the truck sprays the lignin. You can drive on it right away, and it's fully dry in about two hours on a hot summer day. It's built to last the season, and it's especially good on roads with more dirt and sand in them.

Per the product, lignin is described as safe for animals, plants and people, non-corrosive and non-toxic, and lignin is also used in crop fertilizers. Tell me what grows along the road and where the road drains, and we'll talk it through before we spray.

For when to book around the Rogue Valley's dry season, see when to apply dust control. More on our farm work is on farms, ranches and rural property.