Tag Archive: Rose

Be on the Lookout for Rose Crown Gall

Be on the Lookout for Rose Crown Gall

Crown gall symptoms on roses caused by the bacterium Agrobacterium tumefaciens (Rhizobium radiobacter) – Photo credits: Kamil Duman

A plant with a mature gall that is potentially releasing the crown gall bacterium into the potting media. Photo credits: Susannah Wright

For gardeners, rose enthusiasts and rosarians, each of the many rose diseases is as important as the others. But we can say for sure Crown Gall is one of the most unsightly of the many rose diseases that can been seen currently.

The disease got this name from the large tumor-like swellings (galls) that typically occur at the crown of the plant, just above the soil level. The cause of crown gall disease is a bacterium that resides in the soil, Agrobacterium tumefaciens (updated scientific name Rhizobium radiobacter).

SYMPTOMS

Galls or overgrowth (1/4 inch to several inches in diameter) of host plant tissue typically form at the soil line but also can form on branches or roots. Galls are initially white, spherical, and soft but darken with age as outer cells die. It can either be almost entirely on the surface of the plant and easily detached or can be almost indistinguishable from normal plant tissue except for its greatly enlarged appearance.

The bacterium that causes Crown Gall disease survives and persists in the soil for up to 3 years. It can invade recent wounds on the branches or roots. Swelling can be seen as early as 14 days following entry of the bacterium into the plant. The tissue near the gall can be crushed due to rapid cell enlargement. If vascular tissue is crushed, wilting can result from the restricted water movement.

 

Early stage symptom of Crown Gall on roses can be noticed as the small white galls. Photo credits: Susannah Wright

The galls can enlarge to a quarter size in a short period of time from the initial small galls. Photo credits: Mathews Paret

ABOUT THE BACTERIUM

Agrobacterium uses its genes as a weapon to attack plants. It enters the plant mostly from the soil through wounds on the roots or lower stem or from the branches during plant pruning. Symptoms are caused by the insertion of a small segment of DNA (known as the T-DNA), from a plasmid, into the host plant cell, which is incorporated into the plant genome. When the plasmid links up with the plants own DNA, the altered plant cells start dividing rapidly and uncontrollably, and the root or stem develops a tumor-like swelling.

Galls can range from pea size to softball size. Tiny cracks from freezing temperatures or wound sites can be the site of gall formation. Once the wound compounds are generated, the bacteria detach from the xylem cell walls and are carried upward with water during evapotranspiration to the wound site where they initiate galls. One of the common ways of the spread of the disease is by pruning infected plants and moving the bacterium accidentally while pruning nearby healthy plants.

The crown gall bacterium is a soil pathogen, which means main inoculum source is soil. The bacterium can overwinter in infested soils, where it can live as a saprophyte for several years. The bacterium can easily during field preparation, pruning and irrigation. Insects, nematodes and grafting materials, can also transfer the bacterium.

The galls will turn dark in color as they age. Photo credits: Kamil Duman

 

HOW CAN YOU MANAGE ROSE CROWN GALL DISEASE

  • Plant only disease-free roses. Check very carefully before you buy plants for any kind of galls in the crown or branches. Use good sanitation practices in handling roses.
  • Plant in clean soil. Avoid areas with a history of crown gall infestation.
  • Avoid fields with heavy infestations of root-attacking insects and nematodes.
  • Select well-drained soil and irrigate from clean water sources.
  • Keep grafts and buds well above the soil line.
  • Destroy diseased plants as soon as you notice them to avoid cross-contaminating other plants, or pruning equipment. Also, do not keep infected plants with healthy plants, as the likelihood of accidental transmission through pruning is high.
  • Avoid mechanical injury to plants from tillage and hoeing. Provide winter protection so that the bark does not crack.
  • Disinfect pruning tools between plants. disinfect budding/grafting tools before and after use. Bleach (10%; equivalent to 0.6% sodium hypochlorite), or quaternary ammonium-based sanitizer are effective as disinfectants. Make sure to prepare fresh stock routinely.
  • If crown gall plants are noted, please let your local county extension agent know about it and they will be able to contact us for additional site-specific management plans if needed.

Gall formation at pruning sites indicating contamination of the plant during pruning. Photo credits: Kamil Duman

 

 

Authors: Kamil Duman, Susannah Wright, Fanny Iriarte, Barron Riddle, Gary Knox and Mathews Paret, University of Florida – NFREC, Quincy, FL

 

 

PG

Author: Gary Knox – gwknox@ufl.edu

Gary Knox is an Extension Specialist and Professor of Environmental Horticulture with the University of Florida at the North Florida Research and Education Center in Quincy. Dr. Knox’s research interests focus on evaluating species and cultivars of woody plants for their invasive potential as well as for ornamental characteristics. In addition to research plantings, Dr. Knox is working with a nonprofit volunteer group to develop “Gardens of the Big Bend,” a series of botanical, teaching and evaluation gardens at the Center.

Gary Knox

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/11/06/be-on-the-lookout-for-rose-crown-gall-2/

Be on the Lookout for Rose Crown Gall

Be on the Lookout for Rose Crown Gall

Crown gall symptoms on roses caused by the bacterium Agrobacterium tumefaciens (Rhizobium radiobacter) – Photo credits: Kamil Duman

A plant with a mature gall that is potentially releasing the crown gall bacterium into the potting media. Photo credits: Susannah Wright

For gardeners, rose enthusiasts and rosarians, each of the many rose diseases is as important as the others. But we can say for sure Crown Gall is one of the most unsightly of the many rose diseases that can been seen currently.

The disease got this name from the large tumor-like swellings (galls) that typically occur at the crown of the plant, just above the soil level. The cause of crown gall disease is a bacterium that resides in the soil, Agrobacterium tumefaciens (updated scientific name Rhizobium radiobacter).

SYMPTOMS

Galls or overgrowth (1/4 inch to several inches in diameter) of host plant tissue typically form at the soil line but also can form on branches or roots. Galls are initially white, spherical, and soft but darken with age as outer cells die. It can either be almost entirely on the surface of the plant and easily detached or can be almost indistinguishable from normal plant tissue except for its greatly enlarged appearance.

The bacterium that causes Crown Gall disease survives and persists in the soil for up to 3 years. It can invade recent wounds on the branches or roots. Swelling can be seen as early as 14 days following entry of the bacterium into the plant. The tissue near the gall can be crushed due to rapid cell enlargement. If vascular tissue is crushed, wilting can result from the restricted water movement.

 

Early stage symptom of Crown Gall on roses can be noticed as the small white galls. Photo credits: Susannah Wright

The galls can enlarge to a quarter size in a short period of time from the initial small galls. Photo credits: Mathews Paret

ABOUT THE BACTERIUM

Agrobacterium uses its genes as a weapon to attack plants. It enters the plant mostly from the soil through wounds on the roots or lower stem or from the branches during plant pruning. Symptoms are caused by the insertion of a small segment of DNA (known as the T-DNA), from a plasmid, into the host plant cell, which is incorporated into the plant genome. When the plasmid links up with the plants own DNA, the altered plant cells start dividing rapidly and uncontrollably, and the root or stem develops a tumor-like swelling.

Galls can range from pea size to softball size. Tiny cracks from freezing temperatures or wound sites can be the site of gall formation. Once the wound compounds are generated, the bacteria detach from the xylem cell walls and are carried upward with water during evapotranspiration to the wound site where they initiate galls. One of the common ways of the spread of the disease is by pruning infected plants and moving the bacterium accidentally while pruning nearby healthy plants.

The crown gall bacterium is a soil pathogen, which means main inoculum source is soil. The bacterium can overwinter in infested soils, where it can live as a saprophyte for several years. The bacterium can easily during field preparation, pruning and irrigation. Insects, nematodes and grafting materials, can also transfer the bacterium.

The galls will turn dark in color as they age. Photo credits: Kamil Duman

 

HOW CAN YOU MANAGE ROSE CROWN GALL DISEASE

  • Plant only disease-free roses. Check very carefully before you buy plants for any kind of galls in the crown or branches. Use good sanitation practices in handling roses.
  • Plant in clean soil. Avoid areas with a history of crown gall infestation.
  • Avoid fields with heavy infestations of root-attacking insects and nematodes.
  • Select well-drained soil and irrigate from clean water sources.
  • Keep grafts and buds well above the soil line.
  • Destroy diseased plants as soon as you notice them to avoid cross-contaminating other plants, or pruning equipment. Also, do not keep infected plants with healthy plants, as the likelihood of accidental transmission through pruning is high.
  • Avoid mechanical injury to plants from tillage and hoeing. Provide winter protection so that the bark does not crack.
  • Disinfect pruning tools between plants. disinfect budding/grafting tools before and after use. Bleach (10%; equivalent to 0.6% sodium hypochlorite), or quaternary ammonium-based sanitizer are effective as disinfectants. Make sure to prepare fresh stock routinely.
  • If crown gall plants are noted, please let your local county extension agent know about it and they will be able to contact us for additional site-specific management plans if needed.

Gall formation at pruning sites indicating contamination of the plant during pruning. Photo credits: Kamil Duman

 

 

Authors: Kamil Duman, Susannah Wright, Fanny Iriarte, Barron Riddle, Gary Knox and Mathews Paret, University of Florida – NFREC, Quincy, FL

 

 

PG

Author: Gary Knox – gwknox@ufl.edu

Gary Knox is an Extension Specialist and Professor of Environmental Horticulture with the University of Florida at the North Florida Research and Education Center in Quincy. Dr. Knox’s research interests focus on evaluating species and cultivars of woody plants for their invasive potential as well as for ornamental characteristics. In addition to research plantings, Dr. Knox is working with a nonprofit volunteer group to develop “Gardens of the Big Bend,” a series of botanical, teaching and evaluation gardens at the Center.

Gary Knox

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/10/30/be-on-the-lookout-for-rose-crown-gall/

Northwest Florida Rose Symposium Saturday September 16, 2017

Northwest Florida Rose Symposium Saturday September 16, 2017

On Saturday, September 16th, 2017, from 9AM to 12PM, UF / IFAS Extension Washington County will be providing a rose gardening workshop for gardeners across the Panhandle. Many roses are hard to grow in the Florida Panhandle without investing considerable time and energy into spraying for insect and disease problems. This workshop will teach attendees how to select and sustainably grow roses adapted to the hot-humid conditions of the Southern Gulf Coast. There will be opportunities for outdoor learning and hands-on activities. 

Topics include:

  • Selection of disease resistant rose cultivars adapted to the lower South
  • Resources to obtain hard to find easy care rose cultivars
  • Soil and Nutrient Management
  • Disease and insect management
  • Irrigation
  • Rose Propagation

Participants will be given the opportunity to propagate their own rose and take home their own propagation assembly to grow their own roses from scratch.

Refreshments will be provided and a door prize will be available.

Address: Washington County Ag Center Auditorium, 1424 Jackson Ave, Chipley FL 32428.

Pre Registration required for count: Contact Nikki or Cynthia at 850-638-6180 or email Matthew Orwat at mjorwat@ufl.edu

or register online at eventbrite HERE !

 

PG

Author: Matthew Orwat – mjorwat@ufl.edu

Matthew J. Orwat started his career with UF / IFAS in 2011 and is the Horticulture Extension Agent for Washington County Florida. His goal is to provide educational programming to meet the diverse needs of and provide solutions for homeowners and small farmers with ornamental, turf, fruit and vegetable gardening objectives. Please feel free to contact him with any questions you may have.
http://washington.ifas.ufl.edu/lng/about/

Matthew Orwat

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/08/24/northwest-florida-rose-symposium-saturday-september-16-2017/

Workshop on New and Re-emerging Rose Diseases and Pests, July 11, 1-5 pm.

Workshop on New and Re-emerging Rose Diseases and Pests, July 11, 1-5 pm.

Come to this free workshop to learn about the latest results of University of Florida and national research on roses. Receive hands-on training on symptoms and management of rose rosette disease, rose mosaic disease, crown gall, and rose pests.

 

FL Pesticide CEUs, FNGLA CEUs and GA Pesticide CEUs have been applied for!

 

This program is geared for nursery and greenhouse growers, landscapers, municipal maintenance personnel, Extension personnel, Rosarians, rose enthusiasts and science teachers. Sponsored by Farm Credit of Northwest Florida and Harrell’s.

 

To register for this FREE event, please go to: https://rose-diseases-pests.eventbrite.com

 

 

PG

Author: Gary Knox – gwknox@ufl.edu

Gary Knox is an Extension Specialist and Professor of Environmental Horticulture with the University of Florida at the North Florida Research and Education Center in Quincy. Dr. Knox’s research interests focus on evaluating species and cultivars of woody plants for their invasive potential as well as for ornamental characteristics. In addition to research plantings, Dr. Knox is working with a nonprofit volunteer group to develop “Gardens of the Big Bend,” a series of botanical, teaching and evaluation gardens at the Center.

Gary Knox

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/06/22/workshop-on-new-and-re-emerging-rose-diseases-and-pests-july-11-1-5-pm/

Rose Pruning – A Pictorial Guide

Rose Pruning – A Pictorial Guide

It is said that a picture is worth a thousand words. Please follow as a favorite shrub rose, Belinda’s Dream, is pruned.

 

Belinda's Dream Rose - Before pruning, with dense thick growth. Time to open this plant up !

Belinda’s Dream Rose – Before pruning, with dense thick growth. Time to open this plant up !

 

Start pruning by removing dead and diseased wood. Next remove crossing or rubbing branches, unproductive old growth and weak spindly growth

Start pruning by removing dead and diseased wood. Next remove crossing or rubbing branches, unproductive old growth and weak spindly growth

Shorten remaining growth by about half and look ! Your rose is pruned and ready to bear large flowers on long stems for another season !

Shorten remaining growth by about half and look ! Your rose is pruned and ready to bear large flowers on long stems for another season !

 

PG

Author: Matthew Orwat – mjorwat@ufl.edu

Matthew J. Orwat started his career with UF / IFAS in 2011 and is the Horticulture Extension Agent for Washington County Florida. His goal is to provide educational programming to meet the diverse needs of and provide solutions for homeowners and small farmers with ornamental, turf, fruit and vegetable gardening objectives. Please feel free to contact him with any questions you may have.
http://washington.ifas.ufl.edu/lng/about/

Matthew Orwat

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2015/03/05/rose-pruning-a-pictorial-guide/

Re-emergence of Rose Mosaic Disease in Florida Nurseries and Landscapes

Fig. 1: Chlorotic line patterns on the leaves caused by Rose mosaic disease.

Fig. 1: Chlorotic line patterns on the leaves caused by Rose mosaic disease.

Mathews Paret, Plant Pathologist, NFREC, University of Florida, Gary Knox, Horticulturist, NFREC, University of Florida, & Binoy Babu, Post-Doctoral Fellow, NFREC, University of Florida

Roses are one of the most popular flowering shrubs in the U.S with a wholesale value of $ 194 million. Florida is the fourth largest producer of roses, with over $ 20 million in annual sales. Among the virus diseases affecting roses, Rose mosaic disease (RMD) is one of the most important. Prunus necrotic ringspot virus and Apple mosaic virus are the two most common viruses that have been reported to cause RMD. This disease continues to be a major problem in nursery production and landscapes in 2014, leading to major losses in the marketability of roses from Florida and Georgia nurseries.

Fig. 2. Bleached appearance of leaves caused by Rose mosaic disease.

Fig. 2. Bleached appearance of leaves caused by Rose mosaic disease.

The symptoms of RMD are highly variable and can include chlorotic line patterns (Fig.1), bleached appearance of the leaves (Fig. 2), blotches on the leaves (Fig. 3), ring spots (Fig. 4), and mottling and distortion of leaves (Fig. 5). Symptom severity can vary during different times of the year, and the peak period for severity this year has been from June-August in North Florida. RMD is known to reduce flower production and plant growth, and also a reduced life span of rose plants.

Fig. 3. Ring spots on leaves caused by Rose mosaic disease.

Fig. 3. Ring spots on leaves caused by Rose mosaic disease.

Fig. 4: Blotches on the leaves caused by Rose mosaic disease.

Fig. 4: Blotches on the leaves caused by Rose mosaic disease.

Fig. 5: Mottling and distortion of the leaves caused by Rose mosaic disease.

Fig. 5: Mottling and distortion of the leaves caused by Rose mosaic disease.

Key points for prevention and management

 

  1. Always, start with clean stock plants and ideally, virus-indexed stock. However, be aware that RMD has been reported from healthy virus-indexed material in the past. The reason of why RMD is found in certified virus-free planting stock is not yet known.
  2. Even though there is no clear evidence on the potential transmission of the viruses causing RMD through pruning equipment or knives, it is important to sanitize equipment consistently when working with roses, to minimize any potential risks.
  3. Field-to-field spread of RMD has not been definitively determined yet; however, potential for transmission of viruses causing RMD through natural root grafting between closely spaced plants is a possibility, as indicated in a previous study by Golino et al. in 2007.
  4. Commercial nurseries should remove infected plants immediately, as a single infected plant in an entire shipment can lead to rejection of the supply, and could be a risk to other plants in production (even though modes of disease spread have not been definitively proven yet).

 

PG

Author: Mathews Paret – paret@ufl.edu


http://nfrec.ifas.ufl.edu

Mathews Paret

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2014/11/14/re-emergence-of-rose-mosaic-disease-in-florida-nurseries-and-landscapes/

It’s in Florida: Rose Rosette Virus, a Devastating Disease on Roses

It’s in Florida: Rose Rosette Virus, a Devastating Disease on Roses

RRV Symptoms 1

Witches’ broom like appearance, abnormal red discoloration of shoots and foliage, excessive thorns, distorted leaves, and deformed buds and flowers are key symptoms for the devastating Rose Rosette Disease

Roses are one of the most popular flowering shrubs in U.S. with a total wholesale value of 194 million U.S. Dollars. Among the major states in U.S., Florida is the fourth largest producer of roses with a total value exceeding 20 million U.S. Dollars. Among the major diseases on roses, Rose Rosette Disease caused by Rose Rosette Virus (RRV), an Emaravirus has been a major problem for roses in many states in the U.S during the last many years. This virus is spread by an eriophyid mite species Phyllocoptes fructiphilus. This disease was not present in Florida until November 2013 when the disease was first discovered and now confirmed in 3 Florida counties, one of which was Gadsden in panhandle Florida.

Severe thorn proliferation is characteristic to rose rosette disease.

Severe thorn proliferation is another characteristic of rose rosette disease.

The key symptoms for Rose Rosette Disease include witches’ broom, excessive thorns, abnormal red discoloration of shoots and foliage, distorted leaves and deformed buds and flowers (click the link below for symptoms). The diseased plants usually die in 1-3 years. Considering the economic importance of the rose plants, and the highly destructive nature of the Rose rosette virus, research is currently underway by scientists at the University of Florida and the Division of Plant Industry-FDACS to develop early detection methods for the virus and management practices. This project is funded by Florida Nursery Growers and Landscape Association, and the University of Florida, IFAS Dean for Research.

Distorted flower bud; leaf developing from flower bud tissue.

Distorted flower bud; leaf developing from flower bud tissue.

Severe yellowing and stunting of the plant. Infected plants usually die in 1-2 years.

How should Nursery Growers Respond:

  1. Routine scouting and early identification. Submit samples for definitive confirmation.

  2. Destroy infected plants. There is no cure for rose rosette disease. Detection will prompt a quarantine by DPI until cleaned up.

  3. Eriophyid mite management in early spring, rotating insecticides with different modes of action.

Note: The Eriophyid mite species described as the vector for RRV is not known to be present in Florida. Thus mite management recommendations are protective in nature.

Further details can be found in the links below.

 U-Scout Pest Alert

Fact Sheets:

 

 

PG

Author: Mathews Paret – paret@ufl.edu


http://nfrec.ifas.ufl.edu

Mathews Paret

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2014/02/21/its-in-florida-rose-rosette-virus-a-devastating-disease-on-roses/