Hop Powdery Mildew

Another major disease we deal with here on the farm is hop powdery mildew. Powdery mildew is a relatively new disease to our area and farm during our third generation of farming. There are some varieties we raise on the farm that are resistant to powdery mildew; these include our Nugget and Cascade. Most all of our other varieties are susceptible to powdery mildew with Galena and the super high alpha varieties (CTZ) being some of the worst.

Powdery mildew has been difficult to manage and can lead to low yields if it gets out of hand. Like downy mildew, powdery mildew starts out in or near the ground, but powdery mildew works its way from the bottom to the top of the bines very quickly, while downy mildew normally stays around the crown. All of our yards are checked at least once a week by professionals as well as by us when we drive around daily.

Burn-Back and stripping are one of the best ways to help control and defend against major powdery mildew outbreaks.

Sadly I do have a few pictures of powdery mildew:

Powdery Mildew spot on a leaf found about five feet from the ground. This is something we would rather not see in our yards.


Close up of burn-back in a high alpha hop yard, notice the foliage browning from the ground to about four feet up.

View down row of super high alpha's that have recently been burnt back.


Links to more information on Powdery Mildew:


Oregon State University -Plant Disease Control:
http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=603


University of Idaho - Plant Soil Entomological Sciences:
http://www.ag.uidaho.edu/PSES/Research/r_ent_hoppest_powderymildew.htm

I'll leave a note next time I leave town.

I apologize to everyone who came looking for new posts this past Thursday, Friday, and Saturday. The author of this blog, me, left the farm late Wednesday night for Phoenix to be a groomsman in a good friend's wedding. Between now and then I have experienced severe Internet withdrawals, but lived through it and have great ideas for more posts in the next week, daily of course.

Hop Yard Height/Size

We have received a few questions regarding the height and size of our hop yards. All of our trellis systems are built with 21-23' lodge pole pine poles, which are placed in the ground to a depth of about 3-4' each. This gives us a ground to top wire height between 18-20' for all of our hop yards. The hop yards themselves range between 9 and 20 acres. During the winter and in early spring we will post more about our trellis systems as this is when we do most of our maintenance on them.

Me standing at the edge of a hop yard, I'm 6'1" just to give an idea of how tall the trellis is.


Strings going into the hills nearby where I am standing in the photo above.

Close up view of how the coir strings are tied off to the top wires. These knots are tied single handed so that two coir strings can be attached simultaneously.


Here is a link to maps showing images of some hop yards, the picture above show me standing in the hop yard (20 acres in size) directly Northwest of the little red pointer tag on the map. The yards located to the north are all square 10 acre yards:

http://maps.google.com/maps?f=q&hl=en&geocode=&q=400+Green+Valley+Road,+Mabton,+WA&sll=46.25828,-120.008769&sspn=0.008427,0.018518&ie=UTF8&ll=46.25831,-120.009713&spn=0.008427,0.018518&t=h&z=16

Hop Downy Mildew

Hop Downy Mildew is a fungus specifically related to hops (Humulus Lupulus), its only host. Downy mildew can be diagnosed in many different ways, but at this stage in the season downy mildew appears as dark blackish spots on the underside of leaves near the crown, hopefully not at all though. In the worst cases if downy mildew is not controlled it will rise up through the bines where it will start to infect the cones, if not addressed before bloom.

Downy mildew can attack hops very rapidly when there are conditions of high humidity and stagnant air in the hop yards (see Burn Back and Stripping). Most of the damage inflicted by downy mildew occurs at the base of the hop, wrecking havoc on the crowns themselves promoting root rot and infecting the shoots in early spring when they rise out of the ground. Here on the farm if we see downy mildew in the yards we do our best control it with increased airflow and the removal of infected crowns from the yards.

Luckily I do not have any pictures of downy mildew at the moment (this is a good thing for us), powdery mildew is another story though. Please feel free to look at the following sites for more detailed information on downy mildew:

Oregon State University Plant Disease Control:
http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=599

University of Idaho Department of Plant, Soil, & Entomological Sciences:
http://www.ag.uidaho.edu/PSES/Research/r_ent_hoppest_downymildew.htm

Burn Back or Stripping Hops

Once the hops reach the top of the wire we either burn back or strip the bottom of the bines nearest the ground. What this entails is removing the leaf and lateral arm matter from the hill to about three to four feet off the ground. We do this for a variety of reasons. One of the major factors is that it helps to increase airflow through the hop yards thereby creating an environment that is less susceptible to mildew.

Burning back or stripping does not lower our yield per acre, due to the fact that a vast majority of the cones will form on the uppermost regions of the bines. In fact removing the growth toward the bottom of the hop allows them to focus more energy toward the top, instead of wasting it on leaves and laterals near the bottom which don’t produce a lot of hops.


Here are a few photos of a yard that has been stripped by hand, which is normally reserved for fields in which mildew is major issue:


High Alpha yard that has been stripped by hand, notice how you can see the twine with only two or three bines wrapped around it.

View across high alpha yard at ground level, notice how there is no foliage remaining near the top of the hills.

1st Year Hop Yards

In the Yakima Valley we are known for some of the greatest hop growing conditions in the world. This means that in normal years a 1st year hop yard can achieve 60-80% yields. In our current season due to abnormally cool conditions the 1st year hop yards are struggling their way up the string.

Our target date on the farm for having our hops reach the wire (the point where the coir twine is tied off to the trellis, usually about 18-20 feet) is the Fourth of July. So that the hops can start focusing on growing more lateral arms where the blooms will later occur.

Here are some photos I took of some 1st year yards on July 3, 2008, trust me they did not reach the wire by the 4th.

1st year yard only a foot off the ground.

1st year Centennial's in the foreground with mature Centennial yard behind them.

1st year Willamette's making better progress than the rest, because they love the cooler Oregon Willamette Valley like weather (hence the name Willamette).

Drip Irrigation Systems

As mentioned yesterday we also use drip irrigation systems (drip) on Puterbaugh Farms. Any new acreage that we plant has drip. There are numerous benefits to using drip in the baby hop yards. With the drip systems we only run our water sets between 2-4 hours once every other day when temperatures are cooler, sometimes we run them daily when the temperature pushes toward triple digits. All of our drip systems are equipped with timers so that the valves change automatically from one to the next. In theory, this would save time, but we still have to keep a watchful eye on our pumps to make sure there is still water flowing. A three hour set, on a timer, without water is useless. Currently we are running four separate pumps with timed systems.

The ability to put fertilizer directly into the water right after it exits the pump is priceless for raising the baby hops. We are able to calculate our fertilizer application with great precision and do not have to use a tractor to apply it. This is not an option in traditional ditches.

In a nutshell we cut the watering time from 36 hours in a traditional ditch system to 2-4 hours with drip and we no longer have to stand there with a shovel all the time. On top of this we can enter the hop yards at any time with a tractor instead of having to wait until the fields dry out enough to run tractors through them.

Drip line running down row of baby Centennials.

Mature hop yard with drip being watered, notice how dry the middle of the row is compared to fields having ditches.

Valve assembly with timer on top.

Close up of timer, this one runs a 3.5 hour set from 11:30 AM to 3:00PM.

Water box in foreground with a pair of pumps and sand filters the large round steel objects, fertilizer unit on the far right.