April, 2001

Dear Friends;

An Integrated Fruit Rot Spray Program
For those growers receiving my Strawberry Newsletter, much of this will be repetitious, but I think this issue is extremely important to all berry growers and bears repeating. Although Botrytis is the main pathogen that usually comes to mind when we think about fruit rot, it is important to realize that it is not the only organism capable of attacking ripening fruit. The fungus Rhizopus can also contribute to fruit rot and be quite aggressive under certain circumstances. Other fungi occassionally associated with rots of ripe raspberry/blackberry fruit include the following organisms: Alternaria, Cladosporium; Penicillicum; Colletotrichum. We usually do not give much consideration to these other potential fruit rot organisms because they have apparently been well controlled by our typical Botrytis spray programs. However, as new fungicides become increasingly narrow in their spectrum of control, it becomes possible that one or more of these organisms may not be controlled. Last August I visited a Marionberry grower who had spent a good deal of effort and money designing the best Botrytis control program he could think of: a rotation of Switch and Rovral. In research conducted in OR and WA by Joe DeFrancesco and Pete Bristow, Switch has consistently performed better than Thiram (very closely related to Ziram) or Captan for Botrytis control. Switch has also been the most effective material for Rhizopus, followed closely by Thiram and then Captan. Work done in the 1980's showed Rovral to be effective on both Botrytis and Rhizopus. Despite some level of Botrytis resistance to Rovral, it is still quite effective, particularly in fields in which it has not been used recently, if used no more than twice during the season. Despite an excellent Botrytis and Rhizopus control program, ripe fruit in this field was rotting. Unfortunately, the causal organisms were never identified, but our plant pathologist did not think the problem was due to Botrytis or Rhizopus. What went wrong?

For many years we have relied on old broad-spectrum fungicides, such as Benlate, Captan, Thiram and Ziram without knowing all of the various fungi they were affecting. Although we were applying them for Botrytis control, they were probably reducing populations of several potential fruit pathogens. We have been so focused on Botrytis, and to some extent, Rhizopus, that we have not given much thought to the other organisms which were being controlled as well. As fungicides become more narrow in their spectrum of control, it is possible that some of these organisms may be able to find a niche and thrive. Until we understand the ecology of different organisms on ripening fruit more fully, the best thing we can do is to continue to incorporate broad spectrum materials into our control programs. Because Botrytis infects through the blossoms, using those materials most effective on Botrytis early in the season makes sense. Because Rhizopus and most of the other rot organisms appear to attack fruit which is already formed, using broader spectrum materials later in the season makes sense.

Looking specifically at the fruit rot fungicides labeled for use in blackberries, we have Switch (OR emergency label granted 4/5/01), Captan (3 day PHI), Ferbam Granuflo (40 day PHI), Rovral (0 day PHI), and Ziram Granuflo or OR-CAL Ziram (can only be used between mid-June and early July). To protect against the development of resistance, Switch and Rovral should not be applied more than twice during the season. Because Captan can be used within 3 days of harvest and our two Ziram products can be used late in the bloom period, it would be a good idea to incorporate one or both of these materials into a rotation.

The fruit rot control options in raspberries are similar to those in blackberries except for fact that there are no Ziram registrations. We are expecting a label for Elevate for Botrytis control in caneberries some time during the next few years. Elevate is even narrower in its spectrum than Switch and can not be expected to control Rhizopus or any other potential rot organism. Given these facts, our old broad spectrum fungicides will continue to remain very valuable to us. It is also important to try to pick fruit in a timely manner so the chances of attack by organisms that attack ripe and over-ripe fruit in the field are minimized.

Blackberry Disease Control – Purple Blotch, Septoria, and Anthracnose
Primocane emergence is the traditional time to begin application of protective fungicides for control of Purple blotch, Septoria, and Anthracnose in EY fields. Purple blotch, caused by the fungus Septocyta ruborum, causes lesions which are purple-brown with red or yellow margins, and anywhere from about 0.5 to 2.0 inches long. These lesions can coalesce to girdle and kill canes. Research recently conducted at NWREC suggests that this fungus sporulates later in the season, when temperatures are more consistently in the 60's to 70's, and that later emerging primocanes are more susceptible to infection. Benlate is among the most effective of fungicides against Septocyta and was very effective at protecting primocanes in our trial last year.

Cane and Leaf Spot, caused by the fungus Septoria ruborum (closely related to Septocyta), causes spots to form on canes and leaves which are small (about 0.12 inch in diameter) and purple or brown with a white center. The lesions caused by the fungus Anthracnose are similar in appearance to those caused by Septoria.

Although we do not really see the symptoms of these diseases until early spring on fruiting canes, the infection actually occurred the previous season when these canes were tender primocanes. Spores from infected fruiting canes rain down upon primocanes as they emerge, causing infection. For this reason, these diseases are generally much more severe in EY than AY fields.

The following regimen of sprays is recommended for control of these diseases in EY fields: Apply fixed copper, Benlate, Captan, Ferbam-Granuflo or Ziram when primocanes are 1 –12 inches high. Repeat using a different fungicide from the list when primocanes are 12 – 18 inches high. A final spray should be applied when primocanes are 24 – 36 inches high.

Rust Control
The predominant rust in red raspberries is Yellow Rust (fuzzy yellow spores on the leaves) caused by the fungus, Phragmidium rubi-idaei. Yellow rust was quite a problem 4 or 5 years ago, however, Orbit, which we were able to use in 1999 and 2000 through an emergency exemption label, appears to have done an excellent job of reducing disease pressure and incidence. This year we received a permanent label for the use of Rally 40 W fungicide (myclobutanil) in caneberries. Because of this permanent registration, we will no longer be requesting an emergency label for Orbit. Rally is considered very effective at controlling a wide range of rust diseases, and we expect it to perform as well as Orbit. Rally is systemic in the plant (eg. moves through the entire plant), has curative properties (eg. can control infection that occurred up to 72 hours prior to Rally uptake by the plant), and also acts as a protectant.. The predominant rust in blackberries is Cane and Leaf Rust (fuzzy yellow spores breaking out of slit-like openings in the canes) caused by the fungus Kuehneola uredinis. Rally should be effective on this rust as well. For rust control, Rally should be applied when fruiting laterals are a few inches long, with a repeat application made prior to the opening of the blossoms. Rally also controls Powdery mildew, which can be a problem in Boysenberries.

Cane Burning
It does not appear as if we will have a label for Aim (carfentrazone) in time for cane burning this year, so there is probably no need to go into any detail about it at this time. Goal has done a reliable job in raspberries and rates of 0.5 pt for Meeker and 0.33 pt for Willamette seem adequate to do a reasonable job without holding the canes back too long or weakening the plants. As always, it is not a good idea to burn back primocanes in raspberry plants that are weak due to root rot or other causes. Goal has always been a bit disappointing at burning back primocanes in Marions. For this reason, some growers have mixed it with 1 pt of Gramoxone Extra to enhance effectiveness. In our work done in the mid 1990's, the addition of a crop oil concentrate (Mor-act) resulted in a better burn than other surfactants.

Root Weevils
What newsletter would be complete without an article on root weevils? Most raspberry growers probably already know that our main problems are the black vine, strawberry and rough strawberry root weevils; that they are all female with each capable of laying up to a few hundred eggs; and that the bulk of the population over-winter as larvae chewing on plant roots. The over-wintering larvae begin to pupate around mid-April and usually begin to emerge around mid to late May. Weevils emerging at this time usually begin laying eggs within about 3 weeks,(eg. early to mid-June). Because each of these weevils has a slightly different schedule, timing sprays to kill adults prior to egg-laying is already a challenge. But, I'm afraid the situation is even more complicated than that described above.

Although the bulk of root weevils over-winter as larvae, a certain number (usually around 5-20%) over-winter as adults. Work by WSU Entomologist Lynell Tanigoshi has shown that over-wintering adults emerge in late March through May and begin laying eggs in 3 to 14 days. The fact that over-wintering adults are laying eggs as I write this newsletter complicates spray timings considerably. Raspberry growers who have religiously followed a well-timed June spray program, but continue to have problems with weevils, may want to consider going out one evening in April with a flashlight, white sheet, and stick and seeing if over-wintering adults are present in the field. Spread the sheet under the plant, shake or gently beat the plant with the stick, and see what insects fall from the plants onto the sheet. Repeat this procedure in a few spots in the field, but particularly in areas where picking crates are usually stacked during harvest. Weevils like to hide in these crates and may tend to congregate more in plants near that part of the field. Although this may not be ones favorite way to spend an evening, it's probably the best way to know whether or not over-wintering adults are complicating attempts at control.

In addition to the weevils mentioned above, some raspberry growers in WA are also reporting damage from clay-colored or woods weevils, which chew and destroy buds. Although these weevils have not been an issue here thus far, it might also be a good idea to examine canes in a few spots in the field for signs of bud damage. Please give me a call if you see something suspicious. Lynell recommends spraying for these weevils in early to mid-April. If these weevils are present in your field, they would also fall from bushes which are shaken or beaten. If you decide to venture out one evening with your sheet and flashlight and end up finding insects you're not sure you can identify, it would also be a good idea to call me so we can get your critters identified.

Brigade WSB was recently granted a permanent label for use in caneberries for root weevil and leafroller control. This means we no longer have to keep requesting the use of it each year. The new label still has a 3 day PHI, but the REI is 4 days, except for machine harvested fields, which have a 24 hr REI. Although Brigade is considered the most effective of our insecticides for adult root weevil control (resulting in about 90% mortality when applied at night; vs about 80 % mortality with Guthion and 70% mortality with Malathion)), it is very hard on important predators, such as the tiny black beetle Stethorus, and usually leads to two-spotted spider mite problems. One way to minimize impact on beneficials is to spray only the lower part of the canopy, rather than the entire plant.

New Red Raspberry Demonstration Planting at NWREC
Last year OSU Plant Breeder, Chad Finn and Bernadine Strik established a new red raspberry demo planting at NWREC. Although there are only 3 plants of each variety, this planting will allow growers interested in the potential of new varieties for fresh market or processing niches to see these varieties all in one place and evaluate the quality of the fruit. This year will be the baby crop. Among the summer-bearing varieties are Coho, Qualicum, Malahat, Tulameen, Kitsilano, Chiliwack, Comox, Canby, Chilcotin, Lewis, WSU 1096, Meeker, and Willamette. Nootka and WSU 1090 will be planted this year. Fall-fruiters include: Amity; Autumn Bliss; Heritage; Fall Gold; Ruby; Redwing; Kiwigold and Goldie. Feel free to come and check out this new planting and let us know if there are any other varieties you would like added

Things to do April/May
Raspberries: This would be a good time to apply Ridomil as a soil drench for Phytophthora root rot control in raspberries. Because Aliette is absorbed by the leaves and then moved down to the roots, it is probably most effective later in the season (from bloom to fall), when plants are moving carbohydrates down to the crown and roots for storage.

Announcements

Blueberry/Caneberry Field Day at NWREC is scheduled for Wednesday, July 18, 2001. We'll send out programs within the next few weeks.

Our new Berry Extension Agent, Dr. Wei Yang (pronounced Way Young) is now on board. Wei will be working primarily with blueberries, but will also be involved with the other berries to some extent. Wei received his Ph.D at Penn State and has most recently been working at Cornell on mineral nutrition and mycorrhizae in blueberries. Field Day would provide a good opportunity to meet Wei for those folks who have not met him by then.

Growers interested in exploring marketing alternatives may wish to get a copy of the following pubs:
1. Marketing Alternatives for Specialty Produce; pub number PNW 241. This newly revised 31 page pub provides valuable info for growers interested in marketing options. It also cites numerous web sites that are very useful. To order this $3.00 pub write to: Publication Orders, Extension and Station Communications, Oregon State University, 422 Kerr Administration Bldg, Corvallis, OR 97331-2119 or call toll free: 800/561-6719.

2. Marketing Strategies for Farmers and Ranchers. This pub is produced by the Sustainable Agriculture Research and Education (SARE) Program and includes actual reports from farmers who have had success trying various avenues of fresh marketing. To view it on the Internet turn to: http://www.sare.org/san/htdocs/pubs. To order a hard-copy write to: Sustainable Agriculture Network, Hills Building Room 10, University of Vermont, Burlington, VT 05405.

I lifted this info from the Pacific Northwest Sustainable Agriculture Newsletter, which is an excellent source of info on a wide range of subjects impacting agriculture. Growers who would like to receive this newsletter should contact WSU Extension Agent, Charles Brun at WSU, 11104 NE 149th St., C-100, Brush Prairie, WA 98606, or by e-mail at brunc@wsu.edu or by phone at 360/254-8436. With processed markets becoming increasingly competitive, learning more about marketing alternatives is a good idea.

Tidbits of Info from the B.C. Meeting

Weeds: Ever wonder where all those weeds keep coming from? According to the weed specialist at B.C., Pigweed produces about 129,000 seeds/plant. Seeds from purslane can remain dormant in the soil for 40 years; common chickweed seed can remain dormant in the soil 10-60 years. One yellow nutsedge tuber can produce 1,900 new plants, which can then produce 7,000 tubers! One way to prevent yellow nutsedge from making so many tubers is with shading either with opaque plastic or a 6 inch deep mulch. Repeatedly cultivating yellow nutsedge when it has no more than 3 leaves is effective. He also reminded us all of the importance of controlling weeds in ditches, fence lines, pathways, etc. to keep them from going to seed. If the bank accounts of most growers were more like the bank accounts of most weed seeds growers would probably be listed in Fortune 500!

Raspberry-Split trellis Research: WSU REsearcher Steve Klauer reported an overall yield increase of about 20% in plots with a 17 to 20 inch wide split trellis. The 17 inch spacing requires at least a 39 inch throat on the picking machine, the 20 inch spacing requires a 50 inch throat. He figures it cost $252/A for cross arms and labor to install them and for additional wire, and $680 -$750/A for pruning and tying. Given these costs and a price of $0.50/lb, he figured that the split trellis would pay for itself in one year.

The Value of Insect Predators: Entomologist Dave Raworth informed us that each Stethorus eats the equivalent of 1000 mite eggs during its development. The main carabid ground beetle found in raspberry fields there eats a number of insects equal to 3 to 4 times its body weight each day! Imagine what our fields would look like if there were no predatory insects.