Olive trees susceptible to the fungal pathogen as Verticillium

Asked November 21, 2015, 8:11 AM EST

Olive trees susceptible to the fungal pathogen as Verticillium Dear Sirs or teachers or colleagues agronomists, Good evening from Greece. I saw some very interesting comments in the web-site by your university, and for that reason I will grasp the opportunity to address you a few questions; I will be quite interested in receiving your scientific or technical advice to make the final combat against the really tricky disease as the fungal pathogen named Verticillium upon my tree crops in the main table olive tree cultivation that I hold in Greece ? Unfortunately until today nor in the university of which coming from as an Agricultural Engineer / Agronomist ( expertise at Soil Science) neither any commercial company and stores across the Greek territory, , they have no clue how to find a solution to this nasty situation or propose me sthg to fight for . The only partial solution was found had been via an Italian house with the product as '' MICOSAT F-WP (100gr), for which wrapped in conjunction with sun-decontamination on the ground ( soil ) gave already some really promising signs of recovery of the crown of an affected olive tree across my field. Given the situation on the ground, I was wondering, if you were kind enough to provide me any sustainable information either by introducing me any technical data sheet of your extensive survey on this subject or giving me any direction for any plant pesticide that will be really promising to the ultimate fight against this pathogen ( Verticillium ) My special thanks for your attention are in direct order to you! ALL BEST TO YOU, WESTEN PART OF GREECE/AITOLOAKARNANIA MR. DIMADIS, Bill / AGRONOMIST SOIL SCIENCE-AGRICULTURAL ENGINEER TEL. 00306944436718 / VD@PARALOS-TECH.GR ; QUAKE@FREEMAIL.GR

California

4 Responses

Soory. I have tried to get several olive specialists in CA. to respond to your question, but have not had any luck.
Perhaps try again later or Google search and call direct.

this goes to MR. Joe HUNNINGS cc: MRS Beth Raney National eXtension Initiative beth.raney@extension.org,

Hello,

Here is some information from the experts in the horticulture field on Olive culture. in California. Here where we deal with most ornamental , non agriculture questions related to verticillium, the standard advice is do not plant verticillium susceptible plants in an area where this pathogen has been confirmed.

Olive Verticillium Wilt Pathogen: Verticillium dahliae

(Reviewed 3/14, updated 3/14)

In this Guideline:

Symptoms and Signs

Symptoms of Verticillium wilt appear when leaves on one or more branches of the tree suddenly wilt early in the growing season; this process intensifies as the season progresses. Death of mature trees infected with Verticillium is possible. Darkening of xylem tissue, a key symptom for distinguishing Verticillium wilt in many crops is frequently not apparent in olives.

Comments on the Disease

The fungus survives from season to season in the soil and probably in the roots of infected trees. In early summer the fungus can be readily isolated from diseased tissue in infected trees. Verticillium wilt tends to be most troublesome in the southern San Joaquin Valley. Some trees recover naturally from an initial infection, but others may die. This mostly depends on the strain of the fungus (defoliating or non-defoliating), the resistance of the cultivar, and the amount of inoculum in the soil.

Management

The most effective management strategies to protect trees from Verticillium wilt are those taken before planting. When considering a new site for an olive grove, avoid land that has been planted for a number of years to crops that are highly susceptible to Verticillium wilt, such as cotton, cucurbits, eggplant, peppers, potato, or tomato. The Verticillium wilt pathogen is usually present in these soils. Soils containing over one microsclerotia per gram of soil should be avoided.

Inoculum levels can be reduced before planting by flooding the fields during summer, growing several seasons of grass cover crops (especially rye or sudangrass) or a combination of these treatments. It is unknown if these techniques decrease inoculum levels to result in significant disease reduction.

Verticillium microsclerotia (fungal survival structures) have been documented to survive for at least 30 years in the soil. When replanting in an area where susceptible perennials were previously grown, remove as many roots of the trees or vines as possible. A resistant rootstock is not available; however some cultivars (Frantoio, Empeltre, and to a lesser extent Koroneiki) have exhibited tolerance to the pathogen (the pathogen can reproduce on the rootstock, but growth and fruit production are not affected by the disease). Use of a Verticillium-tolerant rootstock may not protect the scion, because the pathogen may grow through the graft union. Some tolerance has been reported in the table olive cultivars Ascolano and Kalamon (Kalamata).

After trees have been planted, there is no reliable method of control. Postplant soil solarization has provided inconsistent control in established plantings.

Soil Solarization

Beginning in late spring, cover the surface of an entire block with transparent plastic that has a UV-inhibitor additive. Leave the plastic on throughout the summer and as long as practical. Inferior plastic will break down and render the treatment ineffective. Solarization gives inconsistent results when used in replant spots. For more information, see Soil Solarization: A Nonpesticidal Method for Controlling Diseases, Nematodes, and Weeds.

To: MRS Kirsten Conrad Buhls, ANR Extension Agent, Arlington County Virginia-Environmental Horticulture and Sustainable Landscape Management-Community Garden Development and Advocacy-Volunteer Management-Urban Forestry