Field

conditions shift to favor soybean Phytophthora stem and root rot

By Dylan Mangel - Extension Plant Pathologist, UNL

We typically expect conditions for soybean seedling disease to be ideal early in the season during crop emergence. This season, conditions were dry and the crop experienced limited seedling disease. Disease levels were exceptionally low for oomycete pathogens like Pythium and Phytophthora. These oomycete pathogens are also known as the ‘water molds’, and that name provides a clue for why they were missing this spring. These pathogens rely on water to complete their lifecycle and when it is absent the spores will remain dormant in the soil.

Spores from Phytophthora sojae, which causes the soybean disease Phytophthora root and stem rot (PRSR), can infect soybean plants throughout the season and will often do so if moisture increases midseason. With moisture increasing across the state in the last few weeks, PRSR is beginning to show up on farms.

PRSR symptoms, when infecting plants mid-season, often show up two weeks after a large rain event or even the first irrigation event of the season. Initial symptoms are often plant wilting and leaf chlorosis accompanied by a brown color on the exterior surface of the stem that extends from the soil surface up for two or three nodes (Figures 1 and 2). After these symptoms are present, the plant will typically dry-down quickly and drop leaves.

A key takeaway here is that Phytophthora is not manageable in season. However, this is a controllable disease if management is applied in the correct spot. Therefore, step one is to verify the disease is caused by Phytophthora and to carefully note what areas are experiencing symptoms. With this information, consider management options for the next season.

The first line of management is to select a resistant soybean variety. Varieties that contain a Phytophthora resistance gene are available. Additionally, varieties are commonly rated for Phytophthora field tolerance. Pairing both field tolerance and a resistance gene will provide the best con- trol. However, if you have an area with high infection, consider planting that field last to give the soil more time to warm and dry out. Seed treatments are also effective against PRSR. Mefenoxam and metalaxyl are effective but often require use at increased rates. See the UNL NebGuide: Management of Phytophthora Root and Stem Rot of Soybeans, G1785 for additional seed treatment information.

Important dates August 15-16

August 15, 1969 - Woodstock began in a field near Yasgur’s Farm at Bethel, New York. The three-day concert featured 24 rock bands and drew a crowd of more than 300,000 young people. The event came to symbolize the counter-culture movement of the 1960’s.

August 16, 1777 - During the American Revolutionary War, the Battle of Bennington, Vermont, occurred as militiamen from Vermont, aided by Massachusetts troops, wiped out a detachment of 800 GermanHessians sent by British General Burgoyne to seize horses.

August 16, 1780 - The Battle of Cam- den in South Carolina occurred during the American Revolutionary War. The battle was a big defeat for the Americans as forces under General Gates were defeated by troops of British General Charles Cornwallis, resulting in 900 Americans killed and 1,000 captured.

August 16, 1896 - Gold was discovered in Rabbit Creek, a tributary of the Klondike River in Alaska, resulting in the Great Klondike Gold Rush.

August 16, 1977 - Elvis Presley was pronounced dead at the Memphis Baptist Hospital at 3:30 p.m., at age 42.

2023 Montana Make It With Wool program

The Montana Make It With Wool program is planning for a great year of creativity through our traditional garment making contest, and the Quilt, Appliqué Project, and Afghan contest.

District MIWW contests will be held in October 2023. Specific dates can be found in the 2023 Montana MIWW brochure which is available on the Montana Woolgrowers Association website at mtsheep.org/make-it-with-wool/, the Montana Make It With Wool Facebook page, at your local MSU Extension office, and from our Montana MIWW Director Amanda Powell (aspowell11@hotmail.com).

Please note: All MIWW garment entries and quilt, appliqué project, and afghan entries are due by October 1, 2023. No late entries being accepted.

The Montana Entry Form has specific instructions on what size samples and fees need to be sent to the appropriate directors. The MIWW Entry Form can be found on the Montana Woolgrowers Association website at mtsheep. org/make-it-with-wool/, the Montana Make It With Wool Facebook page, at your local MSU Extension office, and from our Montana MIWW Director and District Directors.

To compete in the Montana MIWW program, the fabric and/or yarn needs to be a minimum of 60% wool to qualify for the MIWW contest. There is a $7 testing fee for each piece of fabric or yarn used in your entry. We encourage sewists to send in their samples early, to assure the testing results are received before the District contest. All samples are to be sent to the Montana MIWW Director (4187 Old Post Road, Havre MT 59501) for testing.

The MIWW competition is open to all who sew, knit or crochet garments with wool fabric or wool yarn. The categories are Preteen (12 and under); Junior (1316); Senior (17-24); Adult (age 25 and older); and Made for Others. Ages are determined as of January 1, 2023.

All participants compete at the District contests. Winners at the District level in the Junior, Senior, and Adult categories advance to the Montana State MIWW competition held in conjunction with the Montana Woolgrowers Convention on December 1st and 2nd, 2023, in Billings. Made for Other category winners move onto the State MIWW competition if the entry meets the category requirements.

The Montana MIWW Quilt / Appliqué Project / Afghan contest continues this year and we can’t wait to see your one-of-a-kind creation. Specific entry information can be found in the 2023 Montana Make It With Wool Quilt / Appliqué Project / Afghan Contest brochure which can be found on the Montana Woolgrowers Association website at mtsheep.org/ make-it-with-wool/, the Montana Make It With Wool Facebook page, and at your local MSU Extension office. Our quilt competition is directed by Jean Harrison who can be reached at 406-7991331 or jeanharrison45@ charter.net for questions.

We are on Facebook!! If you have not liked our page yet, we ask that you go and like it – Montana Make It With Wool.

udders, excellent feet and easygoing disposition.