THE THE ““NEWNEW”” DISEASE IN DISEASE IN TEXAS AFTER FOUR TEXAS AFTER FOUR YEARS: WHEREYEARS: WHERE’’S IT S IT

GOING?GOING?THOMAS ISAKEITTHOMAS ISAKEIT

PROFESSOR AND EXTENSION PLANT PROFESSOR AND EXTENSION PLANT PATHOLOGIST PATHOLOGIST

TEXAS A&M UNIVERSITY TEXAS A&M UNIVERSITY COLLEGE STATIONCOLLEGE STATION

TWO INVASIVE DISEASES: THE OLD AND THE “NEW”

SORGHUM ERGOT: NOT GENERALLY A PROBLEM, BUT IT PREVENTS A FALL SEED PRODUCTION IN SOUTH TEXAS

HEALTHY DISEASED: PROFUSE SECONDARY CONIDIA

IN A FEW YEARS, WE KNEW THE YIELD LOSS POTENTIAL OF SORGHUM ERGOT AND ITS OVERWINTERING PATTERN

WHAT HAVE WE LEARNED ABOUT SOYBEAN RUST SO FAR?

2006 (DRY) – AUGUST DETECTION

SPRAY ADVISORY FOR LIBERTY COUNTY

2% OF 155,000 ACRES

2007 (WET!) – JUNE DETECTION

WIDE-SPREAD SPRAY ADVISORY

88% OF 92,000 ACRES

NEVER FOUND!

2008 (DRY) – JULY DETECTION

SPRAY ADVISORY FOR LRGV

0.1% OF 205,000 ACRES (SEED PRODUCTION) DOLLY!

BROWNSVILLE, TEXAS – 11/15/08

DETECTED 10/13/08 @ R3-4; SPRAYED LATER

SPRAYED NOT SPRAYED

BROWNSVILLE, TEXAS – 11/15/08

DETECTED 10/13/08 @ R3-4; SPRAYED LATER

HARLINGEN, TEXAS – 12/3/08

R5, NEVER SPRAYED

HARLINGEN, TEXAS – 12/3/08

R5, NEVER SPRAYED

2009 (DRY) – NOVEMBER DETECTION

SPRAY ADVISORY FOR LRGV

0.1% OF 195,000 ACRES (SEED PRODUCTION)

PUCCINIA PATHWAY APPLICABLE FOR PHAKOPSORA ONLY IN 2007

WHY THE PUCCINIA PATHWAY WON’T ALWAYS WORK FOR SOYBEAN RUST

IN SOUTH TEXAS :•

- LACK OF A CONSISTENT OVER-WINTERING SOURCE

- NEED FOR RE-INTRODUCTION EARLY IN SEASON

OVER-WINTERING OF KUDZU

FREEZE PROBABILITY (BASED ON 27 YEARS DATA)

AREA OF KUDZU IN EAST TEXAS: EST. 400 A IN FORESTS

DAL

HOU

LUB

ELP

SAT

AUS

50%

100%

OVER-WINTERING: POLK COUNTY, 2/23/08(PROTECTION AND INFECTION (??) FROM LITTER)

(COMPLETELY UNDETECTABLE FOR SEVERAL MONTHS IN 2009)

OTHER HOSTS – CORAL BEAN (ERYTHRINA HERBACEA)

SURROUNDED FOR SEVERAL MONTHS ON 3 SIDES BY SOYBEANS WITH RUST!

BREWSTER COUNTY BLUEBONNETS, 3/11/08

(STILL NOT DETECTED ON THIS POTENTIAL HOST)

NOT WIDESPREAD: ESCAPES?

WIDESPREAD: APPARENTLY NOT A GOOD HOST

OTHER CROP HOSTS?

MOVEMENT FROM ELSEWHERE

NO RUST IN SOUTH TEXAS UNTIL NOV. 2009

TRENDS THAT CAN AFFECT THE INOCULUM SOURCE:

• - INCREASE IN PRODUCTION OF SOYBEANS IN THE LOWER RIO GRANDE VALLEY OF TEXAS AND ADJACENT RIO BRAVO AREA OF TAMAULIPAS, MEXICO

- TWO CROPS PER YEAR IN BOTH AREAS

MONITORING IN MEXICO – RIO BRAVO AREA, SEPTEMBER, 2009

• 2005: TOO LATE TO HAVE AN IMPACT!

• 2006: TOO DRY TO HAVE AN IMPACT!

• 2007: WIDESPREAD, BUT SMALL IMPACT

• 2008: TOO DRY, EXCEPT IN THE VALLEY, DURING A WET FALL

• 2009: CAN’T PREDICT WHAT WILL HAPPEN

CARRY-OVER IN HIDALGO COUNTY, 1/17/08

HIDALGO COUNTY VOLUNTEER SOYBEANS, 2/23/08

VOLUNTEERS: BROWNSVILLE, 2/26/09

•

TEXAS PROGNOSIS:SPRING CROP

FALL OR LATE-MATURING CROP

• MORE LIKELY TO GET A BREAK WITH DRY WEATHER

• CAN TAKE ADVANTAGE OF ADVISORIES

• WEATHER MORE FAVORABLE FOR RUST

• MAKE PLANS TO SPRAY

• NEED TO DESTROY CROP & VOLUNTEERS!

THE MOST COMMON LAND USE IN TEXAS IS ALSO RUST-AVERSIVE