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Degree Days - A Bit Wet And A Bit Wild, Richard O. Pope Jul 2009

Degree Days - A Bit Wet And A Bit Wild, Richard O. Pope

Integrated Crop Management News

Iowa weather continued to track cool and wet as degree days fell just a bit further behind long-term averages. With the cooler weather and precipitation since June 1 registering 168 percent of normal, many fields have remained damp.


Should Hail Damaged Crops Be Sprayed With A Fungicide?, Alison E. Robertson, Daren S. Mueller Jul 2009

Should Hail Damaged Crops Be Sprayed With A Fungicide?, Alison E. Robertson, Daren S. Mueller

Integrated Crop Management News

Last week severe storms hit several counties in Iowa with hail ranging from softball to pea size causing significant crop damage. Hail damage to corn may negatively affect yield potential (see Elmore and Abendroth, 2009) but may have little effect on soybean yield potential (see Pedersen, 2008).


It Is Time To Sample For Corn Nematodes, Gregory L. Tylka Jul 2009

It Is Time To Sample For Corn Nematodes, Gregory L. Tylka

Integrated Crop Management News

There is much discussion about corn nematodes this season, and interest likely will continue or increase in the next few years. Many articles have been published in the agricultural press about changes in corn production practices that may increase the occurrence of these microscopic worms that live in the soil and can damage corn. Numerous quick facts about corn nematodes were reviewed in the Integrated Crop Management News, April 28, 2009.


July Workshops Offer Comprehensive Corn Nematode And Scn Training, Gregory L. Tylka Jul 2009

July Workshops Offer Comprehensive Corn Nematode And Scn Training, Gregory L. Tylka

Integrated Crop Management News

Plant-parasitic nematodes can be a major yield-limiting factor in Midwest corn and soybean production. Iowa State University will be conducting two all-day workshops on the biology, scouting, and management of corn nematodes and the soybean cyst nematode (SCN). The workshops are being held July 29 and July 30 and will be taught by ISU scientists Thomas Baum, Palle Pedersen and Greg Tylka.


Considerations For Soybean Insecticides And Fungicides, Alison E. Robertson, Daren S. Mueller, Nate Bestor, Matthew E. O'Neal, Rebekah Ritson Jul 2009

Considerations For Soybean Insecticides And Fungicides, Alison E. Robertson, Daren S. Mueller, Nate Bestor, Matthew E. O'Neal, Rebekah Ritson

Integrated Crop Management News

Several Iowa agribusinesses are offering soybean growers pest management plans that include applications of fungicide and insecticide. Although combining an insecticide and fungicide may be convenient, the results from our 2008 Pesticide Stewardship trials suggest this is a convenience that may not pay off.


Scouting Foliar Diseases In A Cool Summer, Xiao-Bing Yang Jul 2009

Scouting Foliar Diseases In A Cool Summer, Xiao-Bing Yang

Integrated Crop Management News

So far this season, weather in Iowa has been cool and wet. NOAA’s mid-term weather forecast for the coming 30 days shows that Iowa will have cooler than normal temperatures with above normal precipitation. A cool and wet summer is favorable to soybean diseases, especially foliar diseases. If the weather trend holds, we should see more foliar soybean diseases late this season than a normal year. Fungicide is a means to controlling foliar diseases. To determine if a chemical control should be applied to manage the foliar diseases, scouting is critical.


Scn Females Are Now Apparent On Soybean Roots, Gregory L. Tylka Jul 2009

Scn Females Are Now Apparent On Soybean Roots, Gregory L. Tylka

Integrated Crop Management News

Many Iowa soybean fields may be infested with soybean cyst nematode (SCN) but the infestations may not be known because SCN does not always cause obvious, above ground symptoms. Up to 40 percent yield loss can occur without the appearance of above ground symptoms.


Degree Days - Temperature Roller Coaster, Richard O. Pope Jul 2009

Degree Days - Temperature Roller Coaster, Richard O. Pope

Integrated Crop Management News

Iowa crops continue in good condition as we finish one of the coolest July 4 holidays on record. Each of the last three weeks have alternated between above and below normal temperatures. As of July 5, we have accumulated 87 fewer degree days statewide since May 1 compared with the 30-year average. That is roughly equivalent to 3.5 average July 4 days, so we aren't in terrible shape. The cool-warm-cool pattern appears now to continue as the forecast is for above normal temperatures through the middle of July.


Decision For Fungicide Applications On Corn Looming, Alison E. Robertson, Daren S. Mueller Jul 2009

Decision For Fungicide Applications On Corn Looming, Alison E. Robertson, Daren S. Mueller

Integrated Crop Management News

Even after two full years of multiple trials, applying fungicides to corn is still not a clear-cut decision for growers. Many growers have experienced yield increases; some have not seen yield increases and even have seen yield losses from fungicides. At a cost of $24 an acre, this is not a decision to take lightly.


Signs Of Crazy Top In Corn, Fanny Iriarte, Alison E. Robertson Jul 2009

Signs Of Crazy Top In Corn, Fanny Iriarte, Alison E. Robertson

Integrated Crop Management News

The Plant Disease and Insect Diagnostic Clinic recently received some corn samples with symptoms and signs of crazy top, a disease caused by Sclerophthora macrospora. Symptoms of this disease vary greatly with time of infection and degree of host colonization by the pathogen. Generally, excessive tillering, rolling, and twisting of the upper leaves appear first. Later, infected plants produce a “leafy” tassel.


Degree Days - More Heat And Humidity With Bigger Weeds, Richard O. Pope Jun 2009

Degree Days - More Heat And Humidity With Bigger Weeds, Richard O. Pope

Integrated Crop Management News

Summer burst through the doors with a blast of heat and humidity. Although oppressive to people, it allowed for rapid growth of both crops and weeds. Weeds are a considerable concern in most areas, most notably where pre-plant burn downs were skipped, and where spraying has been prevented by wet fields. Most areas of Iowa gained 20 to 25 degree days more than the average mid-June week.


Degree Days - Cool Weather Continues, Richard O. Pope Jun 2009

Degree Days - Cool Weather Continues, Richard O. Pope

Integrated Crop Management News

A third straight week of cooler than average weather has slowed crop progress across Iowa. Sporadic rainfall has limited field work, and for many fields weeds are a growing concern (pun intended). There has been slow weed response to herbicides, especially with glyphosate. The answer to this lies in getting some warmer weather to stimulate growth. So patience is a virtue.


Soybean Rust Stirring In The South, Daren S. Mueller Jun 2009

Soybean Rust Stirring In The South, Daren S. Mueller

Integrated Crop Management News

Soybean rust is starting to catch the attention of plant pathologists this year. If you peruse the USDA ipmPIPE Soybean Rust Web site, the distribution of soybean rust may not appear much different than in years past. Like before, soybean rust has survived the winter in the South on kudzu, this year in Alabama, Florida, Georgia and Louisiana. Soybean rust also was reported in five municipalities in Mexico in January, but these have been destroyed or are no longer active, so there is currently no known soybean rust in Mexico.


Seedling Diseases Update, Xiao-Bing Yang Jun 2009

Seedling Diseases Update, Xiao-Bing Yang

Integrated Crop Management News

This spring’s cool and wet weather, with accumulated degree days behind average, favors seedling diseases. Fungal pathogens have been reported to cause poor seedling stands in both corn and soybean fields. Infected soybean seedlings are rotted and can easily be pulled from the soil. Infected corn roots are discolored, soft or mushy. Mesocotyles also may have a brown discoloration. Infected corn seedlings often appear yellow or stunted.


Degree Days - Cool Is Cool, Richard O. Pope Jun 2009

Degree Days - Cool Is Cool, Richard O. Pope

Integrated Crop Management News

The month of June opened with a cool week, with about 80 percent of the normal heat accumulated between May 31 and June 7. Although a bit warmer weather would accelerate crop development, Iowa crops are progressing nicely in most areas. Statewide, we have received about 90 percent of the heat for corn and soybean growth as in an average year. We are now 44 base-50 degree days behind average.


Degree Days - Crops In Good Condition Despite Cool Temperatures, Richard O. Pope Jun 2009

Degree Days - Crops In Good Condition Despite Cool Temperatures, Richard O. Pope

Integrated Crop Management News

The 2009 growing season finished off May a bit cool, with degree day accumulations for only one of the nine crop reporting districts, west central, besting its long-term average. May was marginally cooler in the east, although that is not a problem, and crops are off to a great start statewide.


Size Restrictions For Postemergence Herbicides In Corn, Erin W. Hodgson, Richard O. Pope Jun 2009

Size Restrictions For Postemergence Herbicides In Corn, Erin W. Hodgson, Richard O. Pope

Integrated Crop Management News

Stalk borer is native to Iowa and has only one generation per year. Adult stalk borers are grayish-brown moths with white spots along the forewing with a 1-inch wingspan. Adults emerge in early August and lay eggs in grasses and broadleaf weeds until October. Larvae hatch in late April and early May, or when 500 degree days (base 41°F) have accumulated.


Degree Days - From A Brisk Week To A Balmy One, Richard O. Pope May 2009

Degree Days - From A Brisk Week To A Balmy One, Richard O. Pope

Integrated Crop Management News

Although the week of May 10 was seasonally cold; we made up most of that week's lost heat during the week of May 17. Corn planting is nearing completion across Iowa, and soybean planting is wrapping up in some regions as well. Corn fields should be monitored for black cutworm now, based on pheromone trap capture data.


Scn And Corn Nematode Workshops Set For July, Gregory L. Tylka May 2009

Scn And Corn Nematode Workshops Set For July, Gregory L. Tylka

Integrated Crop Management News

The soybean cyst nematode (SCN) is widely considered the most damaging soybean pest in the Midwest. Effective long-term management of SCN requires thorough knowledge of SCN biology and use of field scouting, resistant soybean varieties, and nonhost crops in an integrated management approach. An all-day workshop focused on SCN will be held on Wednesday, July 29, 2009, in Ames. Topics of discussion at the workshop will include:

  • basic biology of SCN
  • how the nematode modifies living soybean cells to support itself
  • proper techniques for in-season scouting and soil sampling for SCN
  • integrated management of SCN to maintain profitable soybean production ...


Scouting Soybean Seedling Diseases, Xiao-Bing Yang May 2009

Scouting Soybean Seedling Diseases, Xiao-Bing Yang

Integrated Crop Management News

With soybean planting completed in some regions, seedlings are emerging in early planted soybean fields. Starting now and continuing for the next two weeks, producers should scout for soybean seedling diseases. Soybean producers may think scouting for seedling diseases is no longer needed due to increased seed treatments. Actually, that is not the case. Different fields have different seedling diseases and no seed treatment is effective to all diseases. Scouting will help determine the necessity of seed treatment for a particular field and the efficacy of seed treatment used.


Check General Root And Mesocotyl Health When Assessing Corn Stands, Alison E. Robertson, Gary P. Munkvold May 2009

Check General Root And Mesocotyl Health When Assessing Corn Stands, Alison E. Robertson, Gary P. Munkvold

Integrated Crop Management News

This growing season has started out cool with slow heat unit accumulation with frequent precipitation events across the state keeping soils wet. Although some are still out planting corn, there are some fields where corn is at growth stage V2. Reports of seedling blights are beginning to filter in.


Degree Days - Brisk, But Basically Ok, Richard O. Pope May 2009

Degree Days - Brisk, But Basically Ok, Richard O. Pope

Integrated Crop Management News

The week of May 10 was seasonally cold; all areas of Iowa fell behind long term average degree-day accumulations. Departures from normal were equivalent to 2.5 days of May growth in northwest Iowa to 3.5 days in southeast Iowa.


Degree Days - Slow But Steady Progress In Planting, Richard O. Pope May 2009

Degree Days - Slow But Steady Progress In Planting, Richard O. Pope

Integrated Crop Management News

Iowa recorded temperatures close to season normals the week of May 4. Seasonal accumulated degree days are hovering near average in all crop reporting districts. Scattered rainfall limited field work in some areas, but statewide another one-fifth of corn acres were planted, raising the planted acreage in Iowa to around 80 percent. Between one-fourth and one-third of the corn can now be rowed. Soybean planting has picked up, and about 20 percent is now planted.


Spring Is Time To Check Alfalfa For Foliar Diseases, Xiao-Bing Yang May 2009

Spring Is Time To Check Alfalfa For Foliar Diseases, Xiao-Bing Yang

Integrated Crop Management News

Early May is the time to check for alfalfa diseases. When spring has cool temperatures and frequent rains, the weather will promote the development of leaf diseases in some alfalfa fields. Knowing the occurrence of alfalfa diseases in early May helps make decisions about the first cutting. High levels of alfalfa foliar diseases such as spring back stem can cause early defoliation before you make the first cut, resulting in yield reduction.


Spring Sampling Not Recommended For Most Corn Nematodes, Gregory L. Tylka May 2009

Spring Sampling Not Recommended For Most Corn Nematodes, Gregory L. Tylka

Integrated Crop Management News

Most Iowa crop producers and agronomists are familiar with the soybean cyst nematode (SCN), but plant-parasitic nematodes also can damage corn. Corn nematodes are not one organism, but rather are a collection of numerous different species that can feed upon and sometimes damage corn. Each year, several instances of nematode damage to corn are discovered in Iowa. Numerous quick facts about corn nematodes were recently reviewed in theIntegrated Crop Management News, April 28, 2009.


Degree Days - Off On A Muddy Track, Richard O. Pope May 2009

Degree Days - Off On A Muddy Track, Richard O. Pope

Integrated Crop Management News

Today's article is the first weekly post that monitors accumulation of degree days through the 2009 growing season. The map below shows the base 50 degree F days that have accumulated in each of Iowa's nine crop reporting districts, and the departure in accumulations from long-term averages.


Quick Facts About Corn Nematodes, Gregory L. Tylka Apr 2009

Quick Facts About Corn Nematodes, Gregory L. Tylka

Integrated Crop Management News

Recent changes in corn production practices in the Midwest may be responsible for an increase in crop damage caused by plant-parasitic nematodes. And new products for corn nematode management will be available to growers in the near future. These recent developments have led to increased interest in corn nematodes among growers and those who advise them.


Early Planting And Soybean Disease Considerations, Xiao-Bing Yang Apr 2009

Early Planting And Soybean Disease Considerations, Xiao-Bing Yang

Integrated Crop Management News

Blessed by good weather, crop planting in Iowa has begun smoothly. During the April 20 crop teleconference, Extension field agronomists reported good progress of corn planting and some soybean plantings before April 20 around Iowa. With the current weather outlook favorable for spring planting, many soybean fields are likely to be planted early (before the end of the first week of May).


Alfalfa Weevil Hatch Is Upon Us, Richard O. Pope, Jon J. Tollefson Apr 2009

Alfalfa Weevil Hatch Is Upon Us, Richard O. Pope, Jon J. Tollefson

Integrated Crop Management News

The map below indicates the accumulated degree days for each of the nine Iowa crop reporting districts. Degree-day information indicates that alfalfa weevil larvae should be hatching this week in southern Iowa. In central Iowa counties, weevils should be hatching by the third week of April; and in northern Iowa, weevils should hatch the last full week of April. That means that fields in southern Iowa should be scouted now.


A 2009 Prediction For Stewart’S Disease Of Corn, Forrest W. Nutter Jr., Alison E. Robertson, Jon J. Tollefson, Richard O. Pope Apr 2009

A 2009 Prediction For Stewart’S Disease Of Corn, Forrest W. Nutter Jr., Alison E. Robertson, Jon J. Tollefson, Richard O. Pope

Integrated Crop Management News

December, January and February temperatures were all colder than average across Iowa. As a result, the risk for Stewart’s disease of corn in 2009 is low to negligible throughout all of Iowa, based on two predictive models. Stewart’s disease, also known as Stewart’s wilt, is caused by the bacterium Pantoea stewartii. An insect vector, the corn flea beetle, plays a critical role in the plant-to-plant spread of this causal microorganism.