How to Manage Plant Pests and Diseases in Your Home Garden
By Matt Kasson, Brian Lovett and Carolee Bull
Home gardening is having a boom year across the U.S. Whether they're growing their own food in response to pandemic shortages or just looking for a diversion, numerous aspiring gardeners have constructed their first raised beds, and seeds are flying off suppliers' shelves. Now that gardens are largely planted, much of the work for the next several months revolves around keeping them healthy.
Contrary to the Biblical adage, we do not necessarily reap what we sow. As researchers specializing in plant pathology and entomology, we have devoted our careers to understanding and managing plant pests and pathogens. We are also gardeners with varying levels of experience and have seen firsthand the damage these insects and disease-causing agents can inflict.
Plant health is essential for seeing your garden succeed all the way to harvest. The United Nations General Assembly has declared 2020 as the International Year of Plant Health to help bring needed attention to pests and diseases that threaten global food production.
Thousands of pests and pathogens are known to target commercial crops, but a few usual suspects are routinely responsible for havoc in gardens across the U.S. Although each organism's preferences vary, a few common tactics can help you detect them and protect your plants.
Start With Prevention
Just as preventive steps like maintaining a balanced diet help keep humans healthy, home growers can take many actions to help their gardens thrive.
One key step is assessing soil fertility – the ability of soil to sustain plant growth – which can vary widely depending on your location and soil type. Low soil fertility limits food production and predisposes plants to disease and pests. University extension soil testing labs can help evaluate the quality of garden soil and identify nutrient deficiencies and acidic soils, often at no charge.
Using weed barrier landscape cloth for planting rows and mulching between rows is an effective way to suppress weeds. Matt Kasson, CC BY-ND
Suppressing weeds, either through mulching or weeding by hand each week, increases air flow and reduces humidity around garden plants, making it harder for pests and pathogens to thrive. Weed control ensures that nutrients are available for the plants you want to grow.
Proper spacing between plants is also important. Crowding can contribute to disease and pest outbreaks, so check and follow recommendations on seed packs or online as you add and move plants throughout the season. You can always cull plants after they come up to help with spacing. In small gardens, fewer plants that are properly supported can produce a bigger harvest than many overcrowded plants.
And then there's the weather. Frost, hail, drought and flooding all pose unique risks to plants. Inconsistent rainfall can kill thirsty plants more quickly than infertile soils. Both too little and too much water will stress plants and can make them more vulnerable to severe pest and pathogen outbreaks.
A general rule of thumb is to follow a consistent daily watering regimen – preferably first thing in the morning – and to avoid over-watering, which can encourage root pathogens in soil.
Common plant pathogens include viruses, bacteria, nematodes, oomycetes and fungi. All of these microorganisms, especially at an early stage of infection, are too small to see. But when they proliferate, they cause changes in plants that we can recognize.
Unlike insects, which move around on six legs or on wings through the air, pathogens can move unseen and unchecked from leaf to leaf on the wind, through the soil or in droplets of water. Some microbes have even formed intimate relationships with insects and use them as vehicles to move from plant to plant, which makes these pathogens even more challenging to manage. Unfortunately, by the time some pathogens make their presence known, the damage is already done.
We recently conducted a Twitter poll of gardeners nationwide to find out which culprits plagued their gardens. People named aphids, squash vine borers, squash bugs and flea beetles as the most problematic insect pests. Their most troublesome pathogens included powdery mildew, tomato bacterial wilt and cucurbit downy mildew.
To manage such perennial challenges, the first step is to spend time closely looking at your plants. Do you notice any insects consistently hanging around, or molds colonizing leaves or other plant parts? How about symptoms such as blight, stunting, or leaves that are yellowing, browning or wilting?
This white fungal growth is an early sign of powdery mildew on a leaf of susceptible summer squash. Matt Kasson, CC BY-ND
There are countless resources online for keen-eyed and curious gardeners looking to identify and manage pests and diseases. Try uploading a photo to the iNaturalist app or a Facebook gardeners group that can offer a community-sourced ID. Plant disease clinics in your state will also diagnose plant damage from diseases and pests for free or at low cost.
Once you've identified a problem serious enough to intervene, the land grant extension system can provide solutions. Extension programs at land grant schools like West Virginia University and Penn State University offer critical information on agriculture and management of pests and diseases in multiple languages for commercial and home growers.
Their resources include information on safe and proper use of pesticides as part of integrated pest management strategies. This approach employs pesticides in a targeted way along with non-chemical control methods and cultural practices, such as choosing native plants. Our professional societies, including the American Phytopathological Society, also offer a compendium series to help users diagnose and treat pests and diseases.
Sow seed for fall transplants of broccoli, kale, turnip, and cauliflower in flats or containers by the 3rd to 4th w… https://t.co/i3chrkKCj0— Montgomery County Master Gardeners - Maryland (@Montgomery County Master Gardeners - Maryland)1593540775.0
Those who are serious about learning and sharing their experience with others may want to consider Master Gardener programs, which train and certify community members on the latest evidence-based gardening techniques, tailored to their growing area. Master Gardeners pay it forward by training new Master Gardeners and answering questions for any gardener.
Plant pests are a daily reminder that gardens do not exist in a vacuum, and gardeners shouldn't struggle alone either. Joining the gardening community takes attentiveness and time, but we believe the investment required to become an active member of your local gardening community is well worth it. With experience, the nervous tightrope act of keeping pests at bay and food on the table becomes a delicate dance that can help us appreciate where our food comes from – and ultimately, our place in the global ecosystem.
Matt Kasson is an Associate Professor of Plant Pathology and Mycology, West Virginia University.
Brian Lovett is a Postdoctoral Researcher in Mycology, West Virginia University.
Carolee Bull is a Professor of Plant Pathology and Systematic Bacteriology, Pennsylvania State University.
Disclosure statement: Matt Kasson receives funding from USDA and The Ohrstrom Foundation. Carolee Bull receives funding from the USDA and from the mushroom industry, and matching funds from seed companies for her research projects. Brian Lovett does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Reposted with permission from The Conversation.
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By Joe Roman and Taylor Ricketts
The COVID-19 pandemic in the United States is the deepest and longest period of malaise in a dozen years. Our colleagues at the University of Vermont have concluded this by analyzing posts on Twitter. The Vermont Complex Systems Center studies 50 million tweets a day, scoring the "happiness" of people's words to monitor the national mood. That mood today is at its lowest point since 2008 when they started this project.
The Hedonometer measures happiness through analysis of key words on Twitter, which is now used by one in five Americans. This chart covers 18 months from early 2019 to July 2020, showing major dips in 2020. hedonometer.org<p>These same tweets also indicate a potential salve. Before pandemic lockdowns began, doctoral student <a href="https://scholar.google.com/citations?user=0P0ZYbIAAAAJ&hl=en" target="_blank">Aaron Schwartz</a> <a href="https://doi.org/10.1002/pan3.10045" target="_blank">compared tweets before, during, and after visits to 150 parks, playgrounds and plazas</a> in San Francisco. He found that park visits corresponded with a spike in happiness, followed by an afterglow lasting up to four hours.</p><p>Tweets from parks contained fewer negative words such as "no," "not" and "can't," and fewer first-person pronouns like "I" and "me." It seems that nature makes people more positive and less self-obsessed.</p><p>Parks keep people happy in times of global crisis, economic shutdown and public anger. Research has also shown that transmission rates for COVID-19 are <a href="https://www.sfchronicle.com/news/article/Is-risk-of-coronavirus-transmission-lower-15287602.php" target="_blank">much lower outdoors than inside</a>. As scholars who study <a href="https://scholar.google.com/citations?user=yFzb2EUAAAAJ&hl=en" target="_blank">conservation</a> and how nature <a href="https://scholar.google.com/citations?user=CCnUeN8AAAAJ&hl=en" target="_blank">contributes to human well-being</a>, we see opening up parks and creating new ones as a straightforward remedy for Americans' current blues.</p>
Park Visits Are Up During the Pandemic<p>According to the Hedonometer, sentiments expressed online started trending lower in mid-March as the impacts of the pandemic became clear. As lockdowns continued, they registered the lowest sentiment scores on record. Then in late May, effects from George Floyd's death in police custody and the following protests and police response once again could be seen on Twitter. May 31, 2020 was the saddest day of the project.</p><p>Recent surveys of park visitors around the University of Vermont have shown people <a href="https://osf.io/preprints/socarxiv/sd3h6" target="_blank">using green spaces more</a> since COVID-19 lockdowns began. Many people reported that parks were highly important to their well-being during the pandemic.</p>
<div id="4c7e4" class="rm-shortcode" data-rm-shortcode-id="bc0ac146ab2a94228f32d973fc2ab272"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1289428912879964160" data-partner="rebelmouse"><div style="margin:1em 0">#Goldengatepark #sf #quarantinemood https://t.co/9l3ufnbkt6</div> — Suvd (@Suvd)<a href="https://twitter.com/Suvd19486406/statuses/1289428912879964160">1596258783.0</a></blockquote></div><p>The powerful effects of nature are strongest in large parks with more trees, but smaller neighborhood parks also provide a significant boost. Their impact on happiness is real, measurable and lasting.</p><p>Twitter records show that parks increase happiness to a level similar to the bounce at Christmas, which typically is the happiest day of the year. Schwartz has since expanded his <a href="https://arxiv.org/pdf/2006.10658.pdf" target="_blank">Twitter study</a> to the 25 largest cities in the U.S. and found this bounce everywhere.</p><p>Parks and public spaces won't cure COVID-19 or stop police brutality, but they are far more than playgrounds. There is growing evidence that parks contribute to mental and physical health in a range of communities.</p><p>In a 2015 study, for example, Stanford researchers sent people out for one of two walks: through a local park or on a busy street. Those who walked in nature showed <a href="https://doi.org/10.1016/j.landurbplan.2015.02.005" target="_blank">improved moods and better memory performance</a> compared to the urban group. And a team led by <a href="https://penniur.upenn.edu/people/eugenia-gina-south" target="_blank">Gina South</a> of the University of Pennsylvania showed in a 2018 study that greening and cleaning up blighted vacant lots in Philadelphia <a href="http://dx.doi.org/10.1001/jamanetworkopen.2018.0298" target="_blank">reduced local residents' feelings of depression, worthlessness and poor mental health</a>.</p>
Creative Strategies<p>It isn't easy to create new parks on the scale of San Francisco's Golden Gate Park or the Washington Mall, but smaller projects can expand outdoor space. Options include greening vacant lots, closing streets and investing in existing parks to make them safer, greener and shadier and support wildlife.</p><p>These initiatives don't have to be capital-intensive. In the University of Pennsylvania study, for example, renovating a vacant lot by removing trash, planting grass and trees and installing a low fence cost only about US$1,600.</p><p>Urban green space is most needed in neighborhoods that have lacked funding for parks, especially given <a href="https://www.nytimes.com/2020/04/08/nyregion/coronavirus-race-deaths.html" target="_blank">COVID-19's disproportionate impact on Black and Latinx people</a>.</p><p>Cities can also create parklike spaces by <a href="https://theconversation.com/with-fewer-cars-on-us-streets-now-is-the-time-to-reinvent-roadways-and-how-we-use-them-140408" target="_blank">closing streets to cars</a>. Many cities worldwide are currently retooling their transportation systems for the post-COVID-19 world in order to <a href="https://thecityfix.com/blog/bicycles-slower-speeds-livable-city-paris-mayor-anne-hidalgo-plans-ambitious-second-term-dario-hidalgo/" target="_blank">reallocate public space</a>, widen sidewalks and make more space for nature.</p><p>Urban designers, artists, ecologists and other citizens can play a direct role, too, creating pop-up parks and green spaces. Some advocates <a href="https://www.bloomberg.com/news/articles/2017-09-15/a-brief-history-of-park-ing-day" target="_blank">transform parking spaces into mini-parks</a> with grass, potted trees and seating for just the time on the meter, to make a larger point about turning so much public space over to cars.</p><p>Or cities can invest a little more. Minneapolis, Cincinnati and Arlington, Virginia, have won <a href="https://www.tpl.org/parkscore" target="_blank">national recognition</a> for their ambitious investments in public park systems. These areas could serve as models for neighborhoods that lack access to parks.</p>
<div id="25fd0" class="rm-shortcode" data-rm-shortcode-id="383f0d2df0237e9359c30dcce6cd6c42"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1276558744835379201" data-partner="rebelmouse"><div style="margin:1em 0">Looking to safely get outside? Check out the best parks for social distancing in this year's top ten ParkScore citi… https://t.co/HJjEtDsrTD</div> — The Trust for Public Land (@The Trust for Public Land)<a href="https://twitter.com/tpl_org/statuses/1276558744835379201">1593190296.0</a></blockquote></div>
A New Park Deal?<p>The United States has historically driven economic recovery with major infrastructure investments, like the New Deal in the 1930s and the 2009 <a href="https://www.investopedia.com/terms/a/american-recovery-and-reinvestment-act.asp" target="_blank">American Reinvestment and Recovery Act</a>. Such investments could easily include nature-positive spaces.</p><p>Parks are not panaceas, as evidenced by the widely publicized <a href="https://www.nytimes.com/2020/07/06/nyregion/amy-cooper-false-report-charge.html" target="_blank">racist confrontation between a white woman and a Black birder</a> in New York's Central Park in early July. But Hedonometer data add to a <a href="https://advances.sciencemag.org/content/5/7/eaax0903?utm_source=miragenews&utm_medium=miragenews&utm_campaign=news" target="_blank">growing body of evidence</a> that they provide <a href="https://doi.org/10.1073/pnas.1807504116" target="_blank">clear mental health benefits</a>. Creating and expanding parks also <a href="https://www.nrpa.org/contentassets/f568e0ca499743a08148e3593c860fc5/economic-impact-study-summary.pdf" target="_blank">generates jobs and economic activity</a>, with much of the money spent locally.</p><p>We believe investments in nature are well worth it, offering both short-term solace in difficult times and long-term benefits to health, economies and communities.</p>
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<div id="7eb49" class="rm-shortcode" data-rm-shortcode-id="83819841e380a7072ec66d3186c160e8"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1291705003984510977" data-partner="rebelmouse"><div style="margin:1em 0">🚨RESPONSE to #Mauritius #OILSpill 🚨 “Once again we see the risks in oil: aggravating the #ClimateCrisis, as well as… https://t.co/PBLioZat6X</div> — Greenpeace Africa (@Greenpeace Africa)<a href="https://twitter.com/Greenpeaceafric/statuses/1291705003984510977">1596801446.0</a></blockquote></div><p>"There is no guaranteed safe way to extract, transport and store fossil fuel products. This oil leak is not a twist of fate, but the choice of our twisted addiction to fossil fuels. We must react by accelerating our withdrawal from fossil fuels," Greenpeace Africa Senior Climate and Energy Campaign Manager Happy Khambule said in a <a href="https://www.greenpeace.org/africa/en/press/11864/greenpeace-africa-response-to-mauritius-oil-spill/?utm_campaign=oil&utm_source=t.co&utm_medium=post&utm_content=single-image&utm_term=mauritius-oil-spill-reactive" target="_blank">statement Friday</a>. "Once again we see the risks in oil: aggravating the <a href="https://www.ecowatch.com/tag/climate-crisis" target="_self">climate crisis</a>, as well as devastating oceans and <a href="https://www.ecowatch.com/tag/biodiversity" target="_self">biodiversity</a> and threatening local livelihoods around some of Africa's most precious lagoons."</p>
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By Gianna-Carina Grün
While the first countries are easing their lockdowns, others are reporting more and more new cases every day. Data for the global picture shows the pandemic is far from over. DW has the latest statistics.
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How Has the Covid-19 Trend Evolved Over the Past Weeks?<p>The situation has improved slightly: 87 countries report more cases this week than last week. </p>
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