How to Scout for Grape Phylloxera in Vineyards



scouting prophylaxis is a critical

component of your vineyard management


it helps with weed and vineyard floor


as moving soil from infested blocks

to non-infested blocks can increase the

spread or the risk of spread

of phylloxera it also is going to be

important for planning

on replanting and knowing where to use

root stocks within your vineyard

and lastly it's important to know where

infections are so that other vineyard

tests can be

conducted in a manner that they're done

from non-infected blocks

to infected blocks feeding resembles

drought stress and could seem like

proper deficit irrigation

but these critters are often found in

healthy looking vines

and we'll show you how and where and

when to scout

so a couple things i want to cover today

When to scout

is when and where

to scout for phyloxera the wear is

actually pretty easy

and that's because of those symptoms

that phyloxora can inflict upon the vine

that gwen talked about

it's mostly related to vine vigor

because phyloxor feeds on the roots

that causes the plant to be water

stressed over time and nutrient stress

and all the other things that happen

when a plant has no roots

right so the interesting thing with

phyloxora is

it oftentimes early symptoms are

probably masked

by our regulated deficit irrigation

practices we're already controlling

canopy vigor through a reduction in


the problem or what you will likely

notice that hey this is

worse than just regulated deficit

irrigation is when you can no longer


the rate at which you are reducing vigor

that's usually a good indicator to maybe

i should look to see if something else

is affecting the vineyard

so the two main things that you're

looking for with in vineyards with

phyloxor really are

a reduction in and vigor in a canopy and

then a

pattern in that reduction in vigor so


for vigor simply just look at the canopy

are the shoots long

are they short you can also use imagery


ndvi that can help you identify areas or

pockets of potential higher stress

plants within the vineyard and that's an

interesting concept this idea of a


so as gwen indicated phyloxera is a soil

borne root pest right

if you do a lot of movement of equipment

or soil movement within the vineyard

phylloxera will move with it

so because of that if you can think of

how we typically manage within a

vineyard row we're dragging

equipment up and down a row so phyloxora

starts off as a single point

source as we move equipment that

potential infestation

spreads so you will start to see pockets

or oval shaped pockets

of vine stress within your vineyard that

is a great place to

start your scouting practices for

looking to

where phylloxera might be so oval shaped


of high vine stress or very low vine


the next question i always get hey


what gwen when do you actually start

scouting for phyloxera

thank you i have a script right there

right right so

when do you scout for phyloxera which is

a great question by our often peanut

gallery gwen hohizel

so when is actually a pretty good

question to scout because a lot of


want to get out there and start scouting

throughout the growing season and

because it's a soil-borne pest

that means you could be doing a lot of

digging for very little output

right actually you may not actually be

able to find the instax insect

the beauty of phylloxera is that it's

pretty temperature sensitive

it doesn't like really cold temperatures

and it doesn't like really hot


so the ideal times to scout for this

thing are when soil temperatures are


so in the early spring and then in the

fall like now

so phylloxera won't start feeding on

roots until the soil itself

is about 64 degrees fahrenheit so you

don't have to start digging much earlier

than that so that's that's pretty nice

the beauty of that too is that's also

when the vine is starting to develop a


so you may even start to see early

symptoms during that time period

at the end of the growing season once

the soil is starting to cool off a

little bit

that's when you'll see a lot of really

high populations of phyloxor on the

roots so it's easier to see

in the fall but you might be able to do

scouting much earlier than in the early


so in the fall if you can imagine right

before harvest we've probably

done regulated deficit irrigation we're

stressing the vines anyway the vines are

starting to shut down

that's when you can really start to

notice pretty severe canopy symptoms

so it's also easier to identify where to

potentially scout in in the vineyard as


so those are the two big things when do

you scout well when the soils are

moderate so in the spring and the fall

and where do you scout you look for

areas in the vineyard that are seemingly


high levels of stress that you can't

really explain otherwise


when you go out to the vineyard you're

going to need a few tools

one is a shovel script not necessary

you're going to need a trowel a pruner

to be able to prune large roots

flagging tape so that you can mark the


that might have infestation and then of

course a hand lens so that you can see

the phylloxera

but if you're like any good entomologist

you might wear these nice oculars

that allow you to look and dig at the

same time

and then lastly you can wear these

fashionable booties to help prevent


they're like masks for your feet so now

that we're suited up

and booted up we can actually start

digging for phyllox syrup

so again when you go into a vineyard and

you you want to potentially

we think about that concept of where we

initially scout we're going to look for

lower vigor sections

like we have here again this is the end

of the season and these uh

these shoots and internodes are not

really that that long

so that's a good place to potentially


and the next step we're going to do is

instead of digging out in the middle of

the vineyard row

we're going to dig where there are

grapevined roots because this insect

feeds on grapevine roots so the best

place to look for it

will be where roots should be so let's

let's do some digging here

oh that soil was nice and not

pre-loosened at all

very beautiful


all righty scalpel thank you

so again we're looking for for roots but

this is a little bit concerning

because i just dig dug two big scoop

bowls and i am not finding

many grapevine roots well if you think

about it that would make sense

this canopy is not very vigorous

something clearly has messed

up the the irrigation and water uptake

for this particular plant

and so notice we're digging we're

digging there is a

not a lot of anything right there

except for maybe this little guy other


thank you

if we look at this this this is

pretty much the only root piece that we

found in this entire section

uh that's that's not too good notice

there's very little roots

it's actually entirely dead and this is

a very common problem with phylloxera

the feeding itself isn't what kills the

plant but it's all the secondary rot


that move in once the vine root is

starting to die

so for example we happen to have found

these other root pieces on a severely

impacted plant

and notice that these main roots totally


dead or dying absolutely no fine root


you're not going to find phylloxera on a

root that has no root hairs for which

the phylloxera can feed

so even though these really symptomatic


are a good place to start don't be

surprised if you can't find enough

any phyloxora on them so if symptomatic


have a really damaged root system and we

can't find phylloxera

the best place to probably find

phyloxora are on vines that look pretty


but are nearby the symptomatic plants so

let's go look at some of those

so as we're moving up the vineyard here

you notice

pretty unhealthy vines oh yeah that's a

good one glenn

definitely not what we want to see with

a clear cut

healthy line as you go up the vineyard

it's easy to see

it's very easy to see so very very small

canopies very small canopies and oh

wait what do we see right across the row

here these are some pretty look healthy

looking canopies gwen and it's easy to

think about because

by lotzer can often move up and down a

row absolutely

absolutely so as we go along as we go


oh what do you know gwen somebody has

pre-dug a hole for us

in which we can look at grapevine roots

that's the power of extension in your


absolutely so let's let's look a little

bit closer


so here we see a bunch of grapevine

roots already in the hole

these roots as you probably already

noticed have a lot more fine root hairs

excellent fantastic or fine fine roots

and honestly

with a healthy vine we even start to

notice some actual active

grapevine phylloxera galls

so here you see these creamy colored

white bulges

that is the root forming a gall as a

result of phylloxera feeding

so the interesting thing here is these

are fresh galls as noted by that fresh

creamy white tissue

but older galls will look pretty similar

to this and honestly look a lot

like dried dark brown mouse droppings on

the plant

so old galls will dry out and die and

those are the ones that look like

mouse droppings fresh galls will be

creamy and white

but again you really only find galls on

plants that have a healthy enough root


to support the smaller root or smaller

root growth

if the vine has no roots you will not

find phylloxera

so let's look for some phyloxera itself

so when you're digging up and looking

for phylloxera

they can be sometimes challenging to see

but what you can see

fairly easily with the naked eye is

gold or yellow specks

along the root what that actually


if you were to look with your hair your

hand lens is

a cluster or a mass of sometimes dozens


individual phyloxora laos so if you


with your hand lens you could see many

many individuals

within that one single gold mass

and you can see them sometimes going all

the way up a root

but it is difficult to sometimes see if

you looked at this and you wanted to see

an individual laos because it's only one

millimeter big

and they sometimes change color from

from pale yellow to dark brown and

that can be challenging and sometimes

they hide underneath

little crevices within this bark but

almost with any uh severe infection

you can see these large gold masses

that's your telltale sign to start using

your hand lens and be able to pick up

on clusters of phylox or laos


Grape phylloxera is an aphid-like insect pest of grapevines. It exists in vineyards world-wide and was first discovered in Oregon vineyards in the early 1990's. It has more recently been found in the eastern reaches of Oregon and Washington's Walla Walla Valley and other areas of eastern Washington, an area thought to be free of this pest. Most of the vineyards in those regions are own-rooted Vitis vinifera cultivars that are highly susceptible to decline by grape phylloxera. This video presented by Washington State University Extension faculty Dr. Michelle Moyer and Gwen Hoheisel, provides good information and visuals on how to identify phylloxera in infested vineyards of eastern Washington. Keep in mind that there may be some slight differences for observing phylloxera in western regions of Oregon due to soil type and temperature differences. Also, phylloxera is not a concern in vineyards that are planted to resistant rootstocks, which are prevalent in much of western Oregon production regions.

For further information about grape phylloxera, see our OSU Extension Publication:

Grape Phylloxera: Biology and Management in the Pacific Northwest

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