Removing The Mask Of Phytophthora

Jeff RichPhytophthora is a pathogen that does not discriminate from crop to crop and because of this, it is the number-one disease of nursery crops nationwide. Phytophthora causes millions of dollars in crop loss each year, partly due to being misdiagnosed or unrecognized, though a majority of crop loss is due to the lack of proper management and sanitation practices. For this reason, Phytophthora is known as the “the plant destroyer.”

Phytophthora is a water mold, therefore it thrives in a wet environment and allows the spores to travel and spread more easily. On top of that, the pathogen is good at reproducing. The spores move into the plant and root tissue under water logged conditions, and it is here that the pathogen is released into the plant and starts to reproduce.

Phytophthora is also great at hiding and its spores can lie dormant for long periods of time, making it difficult to know when an outbreak will occur. Phytophthora can survive in water, soil or any media within a growing environment.

There are more than 100 different varieties of Phytophthora and it is sometimes thought of as a fungus because it acts similarly, but the pathogen affects all plants differently. Typical signs of a Phytophthora infestation are yellow-vein chlorosis, suspicious spots or blotches on leaves, wilting brown-yellowing leaves, dropping of leaves, severe root loss, the presence of canker on root, stems and/or leaves and in severe cases, sudden plant mortality in patches. Some of these symptoms are identical to symptoms caused by natural conditions and other diseases, so it is easy to see the complexity of correctly identifying this disease.

One chemical or practice will not keep Phytophthora away, so how can growers take control of this pest? A program that focuses on the plant, the pathogen and the environment needs to be in place. To ensure all factors are covered, I have come up with an easy to follow program.

1. Sanitation

This first part is essential and often gets overlooked. It is critical to sanitize tools, equipment, structures and even people. Sanitation is important, but it should be noted that cleaning beforehand can significantly help decrease outbreaks. Chemicals shown to be effective for this are Peroxycompounds (hydrogen peroxide and peroxyacetic acid), percarbonates, copper and chlorine, though it is important to note some chemistries don’t kill spores and are harmful for the worker and the environment. It is also important for your sanitation chemicals to have minimal or zero REI to ensure no delays in production.

2. Contaminant-Free Growing Media

Growing media is frequently disregarded in nurseries and greenhouses, but since water and soil are the two major vectors in carrying Phytophthora, growing media needs to be addressed. Separation of growing media and cover is highly recommended and if possible, should be sterilized. There are many economical and effective sterilization chemicals that can be beneficial; one such is peroxycompounds. This chemistry has been deemed a viable alternative when compared to the bromide restrictions and limitations.

3. Water Treatment

It is known that water sources are huge breeding grounds for many pathogens including Phytophthora. Irrigation from ponds suffers from more pathogens than wells, but wells should also be treated. The biofilm within irrigation lines can be full of zoospores, which harbor disease. Treatment of the water as a curative to eliminate biofilm is highly effective, and it reduces spore counts. This is recommended at least once a quarter. Treating water with a maintenance program can also decrease the likelihood of infestation. Quarterly water tests are also recommended.

4. Chemical Rotation

Proper chemical rotation and implementation can significantly reduce the risk of disease. It is important to treat in rotation and treat proactively. Leaning on the same chemical can prove to be less effective and increases the chance of mutation and spread. It is also essential to use a contact, as well as a systemic chemistry, to ensure full environmental coverage. Tank mixing systemic chemistries with broad spectrum contact fungicides also increases the spectrum of activity, minimizing disease risk.

Documented data on spraying potassium phosphate in conjunction with peroxycompounds has been shown to be an effective spray program. Peroxycompounds and fluopicolide with potassium phosphate have also been proven to have results in control and prevention of Phytophthora and other greenhouse and nursery pests.

5. Insect Control

Insects and nematodes can be carriers of Phytophthora zoospores. A proper pesticide program includes instituting a tank mix or rotational program with an insect growth regulator. Azadirachtin-based insecticides can be used to suppress larval and nymph stages of insects, but it is important to look for products that have some anti-feedant capabilities to help suppress insects that have some contact with the plants. Not all azadirachtin products are the same. It is not recommended to use products with a glycogen base because over time, that can act as a food source for unwanted pests.

6. Plant Nutrition

Proper plant nutrition is important for a good defense against Phytophthora. It is essential to make sure to get the proper analysis of your fertilizer program and avoid salt-rich nutrient programs. An effective fertilizer program is balanced and ensures each specific crop is getting the correct amount of nutrients. A healthy immune system can help plants fight this battle. It may be time to reevaluate the current nutrition program or least double check that it matches the current crop’s specific needs and soil conditions.

7. Education

Education is essential to a proper program for Phytophthora control. and implementing a concise program is the best place to start. Growers should check and see how many steps they follow and how many they can add. Checking off all is a daunting task, but starting is pertinent to effective pest control.

Topics: ,

Leave a Reply

More From Crop Inputs...
Four Star Greenhouse Proven Winner Plants At English Garden

May 26, 2015

Retailer To Grower: It’s Time To Offer Services To Local Garden Centers, Too

Retailers wonder why mass merchants are the only ones to receive stocking, merchandising and plant care from growers.

Read More
Greenhouse Electrical System

May 26, 2015

Don’t Let Your Greenhouse Electrical System Come Up Short – Part 1

Ensuring your greenhouse has enough electricity to operate all the equipment that is installed takes planning and consideration of an operation's needs. Part one of two articles on greenhouse electrical systems covers choosing an electrician, meeting immediate and future needs and planning for back-up power.

Read More

May 22, 2015

Nexus Greenhouses Is Optimistic For Expansion Into New Markets

Cheryl Longtin and Mike Porter, who own Nexus Corporation, say they were excited to attend the grand opening of Gotham Greens’ new structure atop the new Whole Foods grocery store in the Gowanus neighborhood in Brooklyn, N.Y., when it opened in December 2013. The project is just one example of some of the new and expanding markets that Nexus Corporation has expanded into over the past few years. Jeff Warschauer, vice president of sales for Nexus, says the company has enjoyed getting to know and working with the founders of Gotham Greens, Viraj Puri and Eric Haley, and Jennifer Nelkin Frymark, the chief agriculture officer, on their innovative approach to business. “They are very excited and work hard internally – just great people,” he says. “From our perspective, it’s great to see that excitement and vision. The employees there are happy and there’s no turnover; they’re only adding new people […]

Read More
Latest Stories
Bee On Flower

May 20, 2015

White House Task Force Releases Pollinator Health Strat…

An interagency Pollinator Health Task Force commissioned by President Obama released its “Strategy to Promote the Health of Honey Bees and Other Pollinators” on May 19. The strategy, released in accordance with the Presidential Memorandum issued last June, is accompanied by a Pollinator Research Action Plan, which outlines needs and priority actions to better understand pollinator losses and improve pollinator health. The recommended actions will be supported by a coordination of existing federal research efforts and accompanied by a request to Congress for additional resources to respond to losses in pollinator populations. Pages 47 through 52 specifically address pesticides and pollinators. The report calls out plant production, native plants, mosquito control and all urban uses in its Pollinator Action Plan. RISE (Responsible Industry for a Sound Environment) says it supports the goals of improving pollinator health and habitat contained in the White House Pollinator Task Force’s release of its National […]

Read More
r3bv2 disease

May 20, 2015

SAF And AmericanHort Ask Government To Take Ralstonia O…

The Society of American Florists (SAF) and AmericanHort want Ralstonia solanacearum, Race 3, Biovar 2 (R3Bv2) taken off a list of animal and plant diseases that the federal government has determined could be misused as terrorist weapons. SAF and AmericanHort submitted formal comments together on the horticulture industry’s science-backed position on the matter. According to Lin Schmale, SAF’s senior director of government relations, extensive research has proven R3Bv2 does not belong on the government’s list of animal and plant diseases that can be misused as terrorist weapons. Every two years, USDA’s Animal and Plant Health Inspection Service (APHIS) requests a public review of the Select Agent list, asking for comments on whether plant or animal diseases should be taken off the current list or added to it. In the floral industry, R3Bv2 can have a devastating impact on geranium (pelargonium) crops, Schmale says, and both the potato and tomato industries also could be adversely affected by introduction […]

Read More
Two-spotted spider mites, adults and eggs

May 18, 2015

Beware Of Spider Mites In Bougainvillea And Mandevilla …

Greenhouse growers need to scout for spider mites on bougainvillea and mandevilla and use appropriate treatments that minimize pesticide resistance.

Read More
CrownBees_Blue-Orchard-Bee-Female_Artz

May 14, 2015

Pollinator Health 2015: What’s Next For Horticult…

The news on pollinators and neonicotinoids continues to fluctuate between good and bad. Research and outreach efforts backed by the Bee and Pollinator Stewardship Initiative help move the industry in a positive direction.

Read More
empress-intrinsic-brand-fungicide

May 13, 2015

BASF’s Empress Intrinsic Fungicide Is Approved Fo…

BASF’s Empress Intrinsic brand fungicide received supplemental labeling, providing California growers with an effective drench fungicide for disease control and plant health. The supplemental labeling is for use on herbaceous and woody plants in greenhouse, nursery container and field production in California. Empress Intrinsic fungicide provides protection against the four major root and crown disease pathogens: fusarium, phytophthora, pythium and rhizoctonia. Research shows Intrinsic fungicides control the broadest range of ornamental diseases while improving plant resilience to quality and reducing stresses that commonly occur during commercial production, handling and transportation. “More and more growers across the country are discovering the benefits of Empress Intrinisic brand fungicide treatments at propagation for rooted plugs, cuttings and seedlings, and in drench applications on transplants during the production cycle to protect against the major root diseases,“ says Joe Lara, senior product manager for BASF ornamentals. “A BASF fungicide program utilizing Pageant Intrinsic and Empress Intrinsic […]

Read More
Green Mum Basket

April 21, 2015

Growers Face Dilemma In Managing Plant Growth

Whether you’re applying plant growth regulators, manually pinching plants or using automated trimming, the most important thing is to find the right balance.

Read More

April 20, 2015

Three Michigan State University On-Demand Webinars Offe…

The first rule of effective insect and disease control for vegetables is to take action to prevent problems before they occur. But in order to do that, you need to have an effective pest and disease management strategy in place that incorporates best practices to ensure a successful outcome. Michigan State University offers three pest and disease management on-demand webinars that will get you started and keep you on the right track.

Read More

April 15, 2015

BASF’s Pageant Intrinsic Fungicide Registration A…

The state of California has approved the supplemental label registration of Pageant Intrinsic brand fungicide for disease control in the commercial production of greenhouse-grown tomatoes and tomato transplants for the home consumer market.

Read More
Egg card used for insect control in Parkway Garden’s retail area.

April 13, 2015

Biocontrols Use Requires Commitment

For some companies, a switch to biocontrols is an easy decision to make. Parkway Gardens of Ontario, Canada, began using biocontrols nine years ago after Erik Jacobsen, the company’s owner, wanted to expose Parkway, its customers and the environment to fewer pesticide products. “Many pesticides were increasingly ineffective, and in Canada, new product registration moves with glacial slowness,” Jacobsen says. “The labor cost of applying pesticides is much greater than using biocontrols.” In addition, it was also an opportunity to market the company’s eco-friendliness to a younger demographic, he says. In a Q & A with Greenhouse Grower, Jacobsen explains what biocontrols and methods have proved effective for Parkway Gardens Greenhouse Grower: In what types of greenhouse structures are you using biocontrols? Erik Jacobsen: Our greenhouses are all poly covered. About half the range is a Westbrook 14-foot at peak gutter-connected block, and the remaining half a mix of quonset-style […]

Read More

April 11, 2015

Lowe’s Announces Commitment To Phase Out Neonicotinoids…

Home improvement retailer Lowe’s companies announced April 9 that it has committed to eliminate neonicotinoid pesticides from its stores in a gradual phase-out over the next 48 months. In response, horticulture industry associations issued a statement that Lowe’s position is surprising, considering the most recent and positive reports on the state of honeybee health and recent peer reviewed research, and that this is an issue for which sound science must take priority.

Read More

April 9, 2015

Survey Snapshot Shows Biocontrols Mainstreaming

Have you incorporated biocontrols into your greenhouse operation? If so, you’ve got plenty of company. An anonymous online survey by Greenhouse Grower magazine in December 2014 of more than 156 ornamental plant and flower growers across the U.S. found 81 percent used biocontrols in 2014.

Read More

March 31, 2015

Manufacturers Are Taking Biologicals To The Next Level

Through acquisitions and new products, many crop protection companies are making firm commitments to the future of the biocontrols industry.

Read More
OxiPhos_BioSafe2

March 23, 2015

BioSafe Makes Label Changes To OxiPhos And ZeroTol 2.0

There have been some recent label changes made to the BioSafe Systems product OxiPhos, a systemic bactericide/fungicide that reduces downy mildew spores when tank mixed with ZeroTol 2.0.

Read More
Nufarm_logo

March 23, 2015

Nufarm Fungicides Now Registered For Use On Edible Crop…

Nufarm Americas announced label expansions for two of its fungicides that will provide more pest management options for the ornamental industry. The Cleary 3336 F and EG fungicides are now registered for use across a wider range of edible crops, including select greenhouse vegetables and transplants, herbs and backyard fruit.

Read More
ColeusDMLeafSporulation_Daughtrey

March 11, 2015

Research Gives Clues For Preventing Coleus Downy Mildew

Maintaining awareness of coleus downy mildew is more important than ever to safeguard these attractive plants for reliable garden performance.

Read More
Rose Rosette on Knockout rose, May 2013. Photo credit: Alan Windham, University of Tennessee

March 2, 2015

Rose Rosette Disease Fight Gets A Boost From Government…

In 2014, $4.6 million was awarded through the Farm Bill to tackle rose rosette disease, a devastating pathogen that affects one of the industry’s most important crops.

Read More
Fig 1 Leafy Gall On Leucanthemum Becky

March 2, 2015

How To Prevent Leafy Gall Before You Lose Plants

Leafy gall is a nasty disease that can go undetected until plant damage is done. Take these steps to protect your crops from infection.

Read More

February 17, 2015

A New Look At Biological Control: Can Plants Affect The…

The success of a biological control program depends on a number of factors including quality of natural enemies, timing of release, release rates and environmental conditions. However, what is typically not taken into consideration is how plants can affect the performance of natural enemies, including attack rate and searching ability. Biological control agents work hard to protect plants, but plants have ways to help themselves, too.

Read More