Alison Robertson

Dr. Alison Robertson is an associate professor of plant pathology and microbiology. She provides extension education on the diagnosis and management of corn and soybean diseases. Her research interests include Pythium seedling disease of corn and soybean and Goss's wilt. Dr. Robertson received her bachelor's degree in plant pathology in 1991 from the University of Kwazulu-Natal, Pietermaritzburg, and came to the United States in 1999 to pursue a doctoral degree in plant pathology at Clemson University. She started working at Iowa State University in May 2004.

Alison Robertson photo
October 11, 2019 7:16 AM

Tar spot is the latest new disease of corn to be observed in the U.S. The disease was first observed in Indiana in 2015. In 2016, it was found in eastern Iowa, Illinois, Michigan, Wisconsin and Florida. Last growing season, the disease caused significant damage to corn in northern Illinois,...

Plant Diseases
September 23, 2019 5:59 PM

As corn fields start to reach maturity across the state of Iowa, we need to start thinking about stalk and ear rots, particularly in terms of scheduling harvest and grain storage. Read on for more details on stalk rots and ear rots and how to scout for them.  

Stalk rots...

Plant Diseases
August 9, 2019 3:57 PM

This past week there have been numerous new reports of tar spot within the Midwest, including Iowa (Figure 1). For updates maps, please visit https://corn.ipmpipe.org/tarspot/

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Plant Diseases
July 22, 2019 9:05 AM

Corn is starting to tassel and beans are flowering so no wonder everyone is asking about fungicides.  We’ve tried to address some of the questions regarding whether to spray or not in this...

Pesticide Education, Plant Diseases
June 23, 2019 5:44 AM

In 2018, tar spot was detected in 12 counties in eastern Iowa. The disease was observed late in the growing season, at did not cause a lot of damage. In Wisconsin, Illinois, Michigan and Indiana, however,...

Plant Diseases
June 5, 2019 4:25 PM

#plant19 has been a year to remember, and not necessarily in a good way. A couple of days ago we talked about anthracnose leaf blight on corn. Although we...

Plant Diseases
June 5, 2019 8:10 AM

With some planting progress still stalled, many of you are probably finding ways to pass the time, possibly scrolling through Twitter. Adding to some of the anxiety, you’re probably seeing photos of diseased seedling corn, by the name of Anthracnose leaf blight. While last week’s...

Plant Diseases
April 29, 2019 1:04 PM

Now that we’re within the time frames for planting to achieve optimal yields for corn and soybean, producers might be getting antsy with the cold, damp weather, and weighing the risks of a potential cold front that can cause damage to germinating seeds or seedlings.

For those that have...

Crop Production, Plant Diseases
June 8, 2018 9:41 AM

Widespread hail occurred in Iowa on 6 June 2018, causing damage to many acres of corn and soybean plants. At this time, most of the corn is in the V6 to V8 growth stages, while soybeans are at the V1 to V3 growth stages. Some areas of the state also received hail injury earlier this season....

Crop Production, Plant Diseases
October 6, 2017 8:44 AM

Over the past couple of weeks we’ve been doing stalk rot assessments at several of the ISU Research Farms including the Southeast Research and Demonstration Farm, the McNay Research Farm, and the Ames Farm. While the plants seemed to be standing well, minus where the raccoons had fun in one of...

Plant Diseases
September 18, 2017 2:30 PM

To help farmers and agronomists identify, scout, and manage corn diseases a new Corn Diseases booklet, published by Iowa State University Extension and Outreach, is now available to crop producers and industry professionals. The up-...

Plant Diseases
July 10, 2017 1:45 PM

Bacterial leaf streak is a new disease of corn that was confirmed in the U.S. last year - as if we don't have enough spots to diagnose on corn!  And, as you might expect, a lot of spots and streaks on corn can be misdiagnosed for bacterial leaf streak.

Over the winter, corn pathologists...

Plant Diseases
May 15, 2017 7:24 AM

Cooler and wetter conditions can effect corn germination and emergence, but they can also provide a favorable environment for seedling diseases.


One research study being conducted by ISU is taking a closer look at seedling diseases in corn. The goals of the...

Plant Diseases
April 18, 2017 12:27 PM

Iowa State University Extension and Outreach is helping Iowa farmers manage weeds, insects and diseases in their fields.

Pest management is key to high yields and quality grain. ISU Extension and Outreach specialists are working to provide the tools and resources farmers need to manage...

Insects and Mites, Plant Diseases, Weeds
July 21, 2016 3:24 PM

This past week I have been busy with disease diagnostic workshops at the ISU Field Education and Extension Laboratory. For those of you who have attended my sessions before, you know that I usually have a quiz that consists of leaves with various diseases and disease look-a-likes or imposters. I...

Plant Diseases
June 13, 2016 1:02 PM

It seems too early in the growing season yet to be seeing corn diseases like Northern Corn Leaf Blight (NCLB), but I happened to spot a few corn plants with NCLB lesions on them in an isolated area in a corn field in southeast Iowa. Why are we seeing NCLB so early? 


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Plant Diseases
June 13, 2016 12:33 PM

It is hot here in Iowa...but not hot enough to discourage us from hand planting a soybean trial evaluating novel germplasm for resistance to Phytophthora root and stem rot (PRR) caused by P. sojae. PRR causes stand and yield losses every year throughout the U.S. 


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Plant Diseases
May 20, 2016 12:29 PM

Several corn fields in southeast Iowa are having disease issues this spring. After visiting with several ag retailers and farmers, I had Alison Robertson and Tom Kaspar, a plant physiologist with the USDA-ARS, out yesterday to look at some fields with issues. When we put all the pieces together...

Plant Diseases
April 20, 2016 11:12 AM

Many of you are aware that a few years ago we collected diseased soybean seedlings from fields across the Midwest and identified organisms associated with the rotted roots. This soybean seedling disease survey was funded by USDA-NIFA and soybean check-off and the identification of the organisms...

Plant Diseases
April 15, 2016 11:12 AM

A couple of weeks ago in a blog post, I shared with you some research we are doing on the effects of cold stress on soybean susceptibility to seedling...

Plant Diseases
April 4, 2016 2:31 PM

Research can be frustrating. For the past 5 years, my lab has been evaluating seed treatments on soybean. In an effort to detect an effect of seed treatment on soybean stand and yield, in 2015 we planted our trials very early (mid-April). A few days later, it rained, soil temperatures dropped...

Plant Diseases
March 16, 2016 7:15 PM

Alison and I spent the week editing the nearly final version of two national publications about corn and soybean diseases. These will be published by our society, APS Press, like the Fungicides for Field Crops ...

Plant Diseases