Thursday, January 2, 2020

Happy New Year and slides from Loudoun County Private Pesticide Certification Course

Happy New Year!
I hope we will have a nice 2020 season.

Here are slides from a Private Pesticide Certification course that was held on 17 December 2019 at Loudoun County. The link will open a pdf file in Google Drive.

Tuesday, November 26, 2019

Virginia Tech is looking for an Assistant Professor - Tree Fruits/Specialty Crop Pathology

Virginia Tech is looking for an Assistant Professor - Tree Fruits/Specialty Crop Pathology

Virginia Tech’s College of Agriculture and Life Sciences is seeking applicants for a tenure track position in Tree Fruits/Specialty Crop Pathology (Job No. 511904) as part of its SmartFarm Innovation Network faculty cluster hire. The cluster hire of 13 new faculty positions will be filled over multiple years within several academic units and Agricultural Research and Extension Centers. Collaborations of cluster hires and existing faculty will enhance interdisciplinary flagship programs at the nexus of digital, biological, social, and physical sciences and engineering with application to agriculture, food, and natural resources. This ambitious vision will create a statewide network of interconnected faculty, partners, and resources for scientific discovery and developing and deploying new technologies. The goal is to increase overall efficiency, resiliency, sustainability, and economic value of food, agriculture production systems, and natural resources and expand Virginia Tech’s global influence in this rapidly evolving domain.

The Tree Fruits/Specialty Crop Pathology position will be located at the Alson H. Smith Jr. Agricultural Research and Extension Center ( near Winchester, Virginia. This is a tenure-track Assistant Professor position with equal appointments in research and extension and a tenure home in the School of Plant and Environmental Sciences at Virginia Tech in Blacksburg, VA. The position is negotiable as either an academic-year (9-month) or a calendar-year (12-month) appointment. The successful candidate will develop a nationally-recognized, externally-funded research and extension program principally focused on managing diseases of apples, peaches and other fruits relevant to Virginia producers, with latitude to pursue other horticultural specialty crop disease research as needs and funding arise. As a contributor to the SmartFarm Innovation Network, the individual will pursue opportunities to contribute knowledge and skills to collaborative research projects addressing relevant aspects of this initiative. Examples might include, but are not limited to: proximal and remote sensing of pathogens and plant bioindicators; development and validation of predictive disease development models; application of contemporary genetics to crop protection (synthetic biology, RNAi-based fungicides, resistance monitoring and management); autonomous or semiautonomous plant management vehicles; DNA-informed germplasm improvement; and the development of post-harvest technologies to suppress microbial decay. The individual will be expected to secure extramural funding, publish in peer-reviewed journals, recruit and mentor graduate students, actively participate in professional societies as well as departmental affairs. The incumbent will work with Virginia Cooperative Extension Agents and other Extension Specialists to deliver research-based educational programs via contemporary training and teaching materials that will serve relevant fruit industries of Virginia, the region, and nationally. Opportunities for international engagement exist and are encouraged.

In addition to the online application, required application materials include:  1) cover letter summarizing qualifications, 2) curriculum vitae, 3) statement of current research interests (1-page limit), 4) statement of extension education and graduate mentoring philosophy (1-page limit), and 5) full contact information for four professional references.  All inquiries concerning this position should be directed to the Search Committee Chair, Dr. Chris Bergh, (540-232-6046).  Review of applications will begin on January 3, 2020 and will continue until a suitable candidate is selected.

Required Qualifications

Ph.D. in Plant Pathology or a closely related discipline at the time of hire; Demonstrated experience in planning and implementing plant disease management research; Record of peer-reviewed publications; Demonstrated ability to communicate research-based Extension information effectively (oral and written) to agricultural producers and other stakeholders.

Preferred Qualifications

Demonstrated familiarity with tree fruit protection and production; Two or more years of post-doctoral training/experience in relevant field; Evidence of successful grantsmanship; Demonstrated ability to be an effective supervisor or team leader.

Friday, August 16, 2019

A list of short PHI materials + reminder on downy mildew

I heard from many that their fruits are ~2 weeks ahead of "average" season, and some early cultivars are already harvested in the southern VA. I should have posted this earlier, but it probably is still applicable to many of us, so, here is a list of fungicides with PHI (Pre-Harvest Interval) equal or shorter than 7 days.  (the list is the same as in 2018, I did not see any additional material with PHI >= 7 days. If I missed any, please let me know.) I cannot cover every single fungicide out there, but I tried to cover common ones. Winemaking considerations can influence fungicide uses close to the harvest too. Make sure to communicate with your winemaker(s) if they have a preference on the use of fungicides, especially copper, sulfur, and captan (I listed several copper materials because they have different PHI or REI.)

For fungicides to be used on cultivars that have more than a month to go, please refer to my previous post.

Please make sure to rotate mode of action. For instance, Botrytis pathogen is well known for quickly developing fungicide resistance, and this pathogen can be resistant to multiple fungicides. I prefer to see a mode of action to be used twice or less per season, especially when we deal with Botrytis (with an exception of fungicides with FRAC code starting with "M"). In addition to proper leaf removal and chemical approach, wound management is very important to reduce the risk of Botrytis. Managing the source of wounds such as insects (esp. grape berry moth), or birds, or powdery mildew at early in the season, can positively impact Botrytis management. Also, I should note that sour rot pathogens also go after wounds.

At Winchester, the night time relative humidity has been very high, above 95%, for four nights in a row. In addition, we have been observing the rapid development of thunderstorms, pretty much every day in the past few days. These conditions favor downy mildew development because downy mildew pathogen prefers to produce spores under dark, humid conditions. Then spores will be spread via rain.

At this point, you do not need to worry about downy mildew infection on clusters; however, they can still infect leaves. Often time, you will initially see infection on the top of the canopy because younger leaves are more susceptible than older ones. Losing the top leaves and laterals are not a big deal; however, once the infection gets severe, it can defoliate many leaves rather quickly (as in the picture below). If you start to lose older leaves, it can affect the maturing process. Since many of us have been having a relatively dry season, you probably do not need to spray expensive materials, but it is probably not a bad idea to use captan or copper or phos acid in your next spray. (but once again, please consult with your winemaker about the last spray of captan or copper that they would like to see. Often time, we say it is better to avoid captan or copper or sulfur within a month of harvest.)

Good luck with the rest of the season!

Wednesday, July 17, 2019

Berry touch/bunch closure disease management reminders

Our Chardonnay clusters are getting larger and berries are starting to touch each other. It feels a bit early, but here are grape disease management reminders at berry touch/cluster closure stage.

Botrytis gray mold: The best management practice is canopy management. Botrytis pathogen likes high humidity, thus, the poorly managed canopy that traps humidity will help them to thrive. This pathogen also needs wounds to develop spores, thus, grape berry moth and other insects plus birds need to be managed too.

There is a number of Botrytis materials such as Rovral and Meteor (FRAC 2), Elevate (FRAC 17), Vanguard and Scala (FRAC 9), Luna Experience (FRAC 7 plus 3), Kenja (FRAC 7), Miravis Prime (FRAC 7 plus 12), Switch (FRAC 9 plus 12), etc. Botrytis pathogen is well known for its ability to develop fungicide resistance, so, please rotate FRAC codes!!

QoI fungicides (FRAC 11) are no longer the effective material for us due to the development of QoI-resistant Botrytis isolates throughout Virginia. Pristine (FRAC 11 plus 7) has been compromised as well. The next timing of application for Botrytis management is at veraison.

Ripe rot and bitter rot: At this point of the season, captan (M4) and QoI (Strobirulin, FRAC 11) fungicides are good options. In addition, we found that Switch (9 plus 12), copper (M1), tebuconazole (3), Aprovia (7), and Ph-D (19) are somewhat effective. However, none of these materials consistently provided satisfactory suppression of ripe rot when we applied these materials by itself in a series of field studies. Thus, please mix two FRAC codes, especially if you have ripe rot issues in the past. The timing of applications will be the same as Botrytis.

Sour rot: A tank mix of the insecticide zeta-cypermethrin (Mustang Maxx) and the antimicrobial hydrogen dioxide (OxiDate 2.0) before a symptom appears (before veraison) to suppress the fruit fly population is the key. In NY, there are reports of Mustang Maxx-resistant fruit flies, thus, please do not overuse it. Two applications should be sufficient. If you don't have OxiDate, Switch also lists sour rot (suppression only), and other broadspectrum fungicides such as captan and copper, probably have some efficacy too.

Speaking of sour rot, please take a short survey below. We try to gain more information from growers so that we can come up with research priorities. It will be closed in 5 days, so, please participate today. It is not only for Virginia. Thus, if you grow grapes in other states or country, we need your opinion too!

Sour rot survey (will open a new window)

Monday, July 8, 2019

Sour rot survey

My colleagues and I are seeking information on sour rot so that we can develop research priorities (and hopefully obtain grants). Many of us suffer from sour rot (remember the last season?), and we need to get our heads together. If you could fill in this short survey, we really appreciate. It should not take more than a few minutes to complete. It is not just for Virginia, so, please feel free to complete the survey if you grow grapes outside of Virginia.

Sour rot survey (will open a new window)

Thank you!!

Downy mildew reminder

Of course, once I mentioned the lack of rainfall, we (i.e., northern VA) were hit by a series of rain. To make things more complicated, we had at least three consecutive nights of warm and humid (RH > 90%) condition prior to the rains. Humid nights encourage downy mildew pathogen to produce spores, and rains will splash spores to healthy tissues. Thus, the risk of downy mildew during recent rain events was very high. (Note: Central VA also had two humid nights in 7/5-7/6 at the Charlottesville airport, but the chance of rain is not high until this Thursday.)

There are a number of materials can be used for protection: captan (FRAC = M4), mancozeb, ziram (FRAC = M3), Revus, Forum (FRAC = 40), Zampro (FRAC = 40 plus 45), Ranman (FRAC = 21)). Mancozeb products have the 66-day PHI, but ziram's PHI is 21 days. Another good option is a copper (FRAC = M1) material, which is more economical than other materials. Copper has good efficacy against downy mildew, and tends to do well under frequent rain condition. There are several newer copper materials that cause fewer phytotoxicity issues even on relatively copper sensitive cultivars (e.g., Cueva, Champ, etc). If you have already having downy mildew issue, use copper, ziram, or captan as the backbone of your spray program.

Both a phosphite material (FRAC = P07) such as Prophyt and Phostrol, as well as Ridomil products (FRAC = 4 plus M3 (MZ) or + M1(Copper)) have a kickback activity against downy mildew (i.e., it can stop the ongoing infection process). Ridomil MZ contains mancozeb, so, we cannot use it at this time of the season due to its 66-day PHI. Ridomil Gold Copper has a 42-day PHI, so, you may able to use it, depending on the cultivar. Please note that Ridomil is known to have resistance issues, thus, let's limit the use of Ridomil to twice a season at the most. We also have seen multiple Revus-resistant isolates in VA.

So what to do, if you are not sure your previous fungicide application was sufficient (e.g., applied more than 10-14 days ago and/or received more than 2 inches of rain)? 

Options are:
A) a phosphite or Ridomil Gold Copper plus captan or ziram
B) a phosphite or Ridomil Gold Copper plus Revus/Forum or Zampro or Ranman. 

These mixes provide both protective and kick-back activities. 

Friday, July 5, 2019

A quick reminder about powdery mildew

It depends on where you are, but in northern VA, we are having relatively "dry" weather this summer. We have some rain events here and there, but overall, the air is humid, but not wet. Such a condition promote powdery mildew development, so, I just want to provide a reminder on powdery mildew management.

(Powdery mildew symptom on a cluster: the picture was taken this morning)

Powdery mildew pathogen thrives under shaded condition  (i.e., overcrowded canopy). Thus, canopy management is a very important aspect of powdery mildew management.

Chemical management options: Sulfur (FRAC = M2) is an economical option. Copper (FRAC M1) works too, but compared with sulfur, copper seems to be slightly less effective. Other options are: DMI fungicides (e.g., Rally, Elite, Mettle, Rhyme, etc, FRAC 3), Quintec (FRAC 13), Vivando (FRAC 50), Luna Experience (FRAC 7 plus 3), Topguard EQ (FRAC 11 plus 3), Rhyme, Kenja, and Aprovia (FRAC 7), Torino (FRAC U6), etc. Please make sure to rotate FRAC groups. Try to limit the use of a particular FRAC group to twice a season with an exception of FRAC group starts from M.

Fungicide resistance issues: QoI (FRAC 11, e.g., Abound, Flint, etc.) = widespread in VA. I would not count on the QoI material for powdery mildew management. Quintec (FRAC 13) = limited occurrences, but there is a recorded case in VA. There is evidence of DMI-resistant powdery mildew isolates in VA, thus, please do not overuse or rely heavily on DMI products.

If you have an outbreak that cannot stop, please use sulfur or copper (i.e., do not spray the material with FRAC group starts with a number). Also, Kaligreen, Armicarb, and other potassium bicarbonate (FRAC M) are effective; however these materials tend to be expensive. Stylet oil (FRAC M) can be used on on-going powdery mildew too; however, please note that you cannot mix (or use within 14 days) oil and sulfur (the same is true with oil and captan).