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Whitefly-transmitted viruses in vegetable crops

Sep 26, 2018 | Written by                                                                                           We are currently detecting a variety of whitefly-vectored viral diseases in vegetable crops. The two of greatest concern are cucurbit leaf crumple virus and tomato yellow leaf curl virus. Both have been detected in multiple counties in southern Georgia but are generally at low levels to date; unfortunately, this could change rapidly. Current levels of virus infection are similar to late spring (in normal years) but with the obvious difference of large whitefly populations to spread these viruses. The only good news with this is that infection is occurring much later in the season than the last two years and will have less impact on overall yield.

In test on station, I noted obvious leaf crumple virus in less than 5 percent of young squash plants but terminal growth with questionable symptoms was likely in the 25 to 50 percent range. Again, with the relatively high whitefly population we have in Tifton, even a low level of virus can spread rapidly.

Tomato yellow leaf curl virus has also been detected, but generally at lower levels (with the exception of one field reported to be near 100 percent). Again, under conditions with high whitefly populations, any whitefly-vectored virus can spread rapidly.

Fall gardens need sun, good soil, Georgia-friendly plants

By Beverly Adams for CAES News

Temperatures are dropping, leaves are falling, and home gardeners are beginning to plan their fall vegetables.

If you’re new to food gardening, University of Georgia Cooperative Extension offers tips that should lead to a successful fall harvest.

Establish the garden in a location that receives full sunlight, from six to eight hours per day.

Prepare the soil before planting based on soil test recommendations. A laboratory soil test takes the guesswork out of determining whether the soil needs fertilizer or lime to nourish your fall garden crops.

To have your soil tested, visit the Extension website for directions on taking soil samples. Then bring your dry soil sample to your local Extension office with the $10 testing fee.

Plant fall vegetables on schedule and use varieties that are recommended for Georgia. For a list of recommended cultivars and planting dates, refer to UGA Extension Circular 963, “Vegetable Gardening in Georgia,” at extension.uga.edu/publications.

Control weeds, pest insects and diseases.

When Mother Nature does not supply rainfall, water your garden thoroughly at soil level.

And, as always, if you have any questions, contact your local Extension office at 1-800-ASK-UGA1 for advice.

Leafy vegetables thrive in Georgia fall gardens

By Beverly Adams for CAES News

Just the other day I received an email from a Forsyth County resident about a cucumber plant that was in decline. He wanted to know what to do to get it back to “normal.” My response was, “There is nothing to do. It’s the end of the season for that cucumber plant, so pull it up and start thinking about a fall garden.”

As summer vegetables stop producing, it’s time to start planning and preparing fall gardens. One advantage of gardening in the fall is cooler temperatures that make gardening more pleasant.

Another advantage is that most fall vegetables are leafy, green plants that don’t require pollinators to produce the parts we eat. Gardeners can use low-tunnel hoop houses to protect their plants from pests and to capture a few more growing days out of the fall season.

In addition to excluding pests, covering hoop houses in shade cloth blocks out some of the heat from the sun, allowing us to plant cool season vegetables earlier. Later in the season, the shade cloth traps heat from the earth inside the hoop house and can raise the temperature around the plants by a few degrees. Some cool-season vegetables can overwinter in the garden for an early spring harvest.

Because they take longer to mature, some fall vegetables are best purchased as transplants. These include broccoli, Brussels sprouts, cabbage and cauliflower. Vegetables that can be planted as seeds include beets, bunching onions, carrots, collards, kale, lettuce, mustard, radishes, spinach, Swiss chard and turnips.

University of Georgia Cooperative Extension recommends this list of cultivars of cool season vegetables that do well in Georgia:

Broccoli – ‘Marathon’, ‘Packman’, ‘Patriot’, ‘Premium Crop’, ‘Bravo’, ‘Decathlon’

Cabbage – ‘Blue Dynasty’, ‘Bravo’, ‘Early Round Dutch’, ‘Rio Verde’, ‘Green Jewel’

Carrot – ‘Chantenay’, ‘Scarlet Nantes’, ‘Sweetbites’, ‘Sweet Delight’

Cauliflower – ‘Absolute’, ‘Early Snowball’, ‘Graffiti’, ‘White Magic’, ‘Symphony’

Collard greens – ‘Blue Max’, ‘Georgia Southern’, ‘Hevi-Crop’

Kale – ‘Vates’, ‘Dwarf Siberian’, ‘Blue Armor’, ‘Blue Knight’

Lettuce – ‘Butterhead’, ‘Romaine’, ‘Buttercrunch’

Mustard greens – ‘Florida Broadleaf’, ‘Southern Giant Curled’, ‘Red Giant’, ‘Savannah’

Onion, green – ‘White Portugal’

Onion, dry bulb – ‘Burgundy’, ‘Excel’, ‘Grano’, ‘Red Creole’, ‘Savannah Sweet’

Radish – ‘Cherry Bell’, ‘Scarlet Globe’, ‘Champion’

Spinach – ‘Melody’, ‘Winter Bloomsdale’

For more information about planning your vegetable garden at any time of year, see UGA Extension Circular 943, “Vegetable Garden Calendar,” at extension.uga.edu/publications.

Watermelon Research Field Day

2018 UGA Watermelon Research Field Day in Cordele

 

The demonstration trial evaluates the effects of fumigation and fungicide for management of Fusarium wilt in watermelon.

 

Details for the Field Day:

UGA Field Trial Site at Cordele, GA

Address. 1176 US Highway 280 W; Cordele, Georgia

Date: Thursday June 28th, 2018

Time: 9:30 a.m.

 

Downy Mildew of Cucumber Detected in South Georgia

By Bhabesh Dutta, Downy mildew of cucumber has been detected from the Brooks County, GA. These observations indicate that inoculum of downy mildew is currently in southern GA counties  and under favorable conditions  potential disease outbreak in other cucurbits  can occur. I would suggest our cucurbit growers to look for the downy mildew symptoms in their fields and start applying protective spray of below stated fungicides.

 

 

 

Watermelon: Rotation (foliar application)  with  Orondis ultra (provide protection against both Downy and P. capsici);

Elumin+Bravo/Manzate;

Ranman+Bravo/Manzate;

Previcur flex+Bravo/Manzate

 

Please do not use Bravo after fruit set.

 

Other cucurbits: Orondis opti;

Elumin+Bravo;

Ranman+Bravo

Previcur flex+Bravo

 

If Orondis was used as a soil application, please do not use it as foliar (use restriction according to label).

 

 

Some relevant information on Powdery mildew of cucurbits

Powdery mildew is a common disease of cucurbits under field and greenhouse conditions in most areas of the United States.  Although all cucurbits are susceptible, symptoms are less common on cucumber and melon because many commercial cultivars have resistance. This disease can be a major production problem if not manage timely.

Podosphaera xanthii and Erysiphe cichoracearum are the two important fungal organisms that cause cucurbit powdery mildew. P. xanthii is a more aggressive pathogen than E. cichoracearum.  E. cichoracearum requires a lower temperature optimum and hence, this fungus is found mainly during cooler spring and early summer periods. In contrast, P. xanthii are more common during the warmer months.

The causal fungi are obligate parasites and therefore cannot survive in the absence of living host plants. Possible local sources of initial inoculum include conidia from greenhouse-grown cucurbits, and alternate hosts. Verbena, a common ornamental plant and also a common weed, could be an important source of inoculum.

Pathogenically distinct races of Podosphaera xanthii have been differentiated on muskmelon.  Races 1 and 2 have most common in the eastern United States recently.

Fungicides: Quintec, Proline, Torino (rotation in watermelon and cantaloupe)

Proline, Torino, Procure (rotation in other cucurbits)

FSMA (Food Safety Modernization Act ) On-Farm Readiness Review Voluntary Registration

 

http://agr.georgia.gov/farm-safety-program.aspx

 

Farm Safety Program – Ga Dept of Agriculture

agr.georgia.gov

Sign-up to receive the latest information: The best way to protect Georgia’s produce is by working together. Please assist us by identifying your farm and providing your contact information in order to receive important tips and updates regarding the implementation of the Produce Safety Rule.

 

What is an On-Farm Readiness Review?

 

An On-Farm Readiness Review, or OFRR, is a voluntary program offered by the Georgia Department of Agriculture Farm Safety Program. An OFRR consists of a non-regulatory, pre-inspectional visit to farms growing covered produce. An OFRR is NOT an inspection but is about educating before regulating. The goal of an OFRR is to provide farmers with useful information so they can comply with the federal Food Safety Modernization Act.

If you have any additional questions, please contact the Georgia Department of Agriculture Farm Safety Program at (229)-386-3488.

Tank-Mixing Chemicals

Dr. Eric Prostko with University of Georgia shared some information on tank-mixing pesticides:

Tank-mixing pesticides can be rather complicated especially when numerous products will be mixed.  Here are a few questions and answers based upon some recent inquiries that I have received:

1) Can I tank-mix Prowl EC and Prowl H20?

I have never have done this in my research plots but I recently conducted a small tank-mix test (Figure 1).  With good agitation, I did not observe any problems.  Do not mix these two herbicides together before putting in water.  They should be put in spray tank (already filled with water) separately.

Figure 1.  Prowl H20 3.8ASC + Prowl 3.33EC Tank-Mix (32 oz/A of each in 15 GPA, Prowl H20 was put in 1st)


2) Can I tank-mix dry and liquid Valor formulations together in a spray tank?

I have never done this either in my research plots but I conducted another small tank-mix test (Figure 2).  With good agitation, I did not observe any problems.  Remember, it is always a good idea to pre-slurry dry formulations in water before dumping into a large spray tank.

Figure 2.  Valor SX 51WG + Valor EZ 4L Tank-Mix (3 oz/A of each in 15 GPA)

3)  When tank-mixing various pesticides, what is the correct mixing order?  

The general formulation science mixing order is as follows:

a) water soluble bags (WSB)
b) water soluble granules (WSG)
c) water dispersible granules (WG, XP, DF)
d) wettable powders (WP)
e) water based suspension concentrates/aqueous flowables (SC, F)
f) water soluble concentrates (SL)
g) suspoemulsions (SE)
h) oil-based suspension concentrates (OD)
i) emulsifiable concentrates (EC)
j) surfactants, oils, adjuvants
k) soluble fertilizers
l) drift retardants

For those Millennials out there that sleep with their cell phones taped to their head or hands, there is an app called Mix-Tank (Precision Laboratories) that you might find useful (http://www.mixtankapp.com/). There might be some other apps out there that I am not yet aware of?

4) How do I mix Reflex and Gramoxone?

a) add 1/2 of the required amount of clean water into the spray tank
b) start up and maintain tank agitation
c) add NIS
d) add Reflex
e) add Gramoxone
f) add remaining amount of clean water

5) How do I mix Atrazine and Halex GT?

a) add 1/2 of the required amount of clean water into the spray tank and start/maintain agitation
b) add AMS (**only if water quality sample indicates need)
c) add NIS
d) add atrazine (make sure atrazine is fully dispersed before adding other products)
e) add Halex GT
f) add remaining amount of clean water

Seedcorn Maggots in Transplanted Crops

Problems with seedcorn maggots in transplanted crops are popping up all over south Georgia this Spring. While this is a rare occasion (use of transplants avoids many soil borne insect problems), that makes it no less severe when it occurs. Maggots can kill tender young transplants, but cause minimal injury once the plants become established and harden off.

The adult files look like small house flies and are attracted to decaying organic matter. For this reason, they tend to be worse in fields where manure, weeds or a cover crop were plowed in just before planting. For future reference, it is generally recommended that this plowing occur at least three weeks before planting/transplanting. They still can occur in “clean” fields as the transplant media, which is high in organic matter, can attract flies once it is planted into the field.

Seedcorn maggots are worse under cool, moist conditions. This both slows the growth of the plant so that it is susceptible to damage for a longer period and is favorable to the maggots. One research report from Purdue indicated that damage to transplants dropped dramatically (from 60 to 80 percent down to 10 to 0 percent) as soil temperature increased above 70 degrees.

There are no effective rescue treatments for seedcorn maggot infestations. A pre-plant treatment with diazinon should avoid this problem, but is rarely done as the problem is rare. A foliar application with a broad spectrum insecticide after setting/resetting the plants should help suppress fly activity in the field and buy some time for plants to become established.

Lorsban in Sweet Potatoes

Lorsban 24C Label for 60 Day PHI in Sweet Potato

 

While it has taken several years, Georgia does now have a 24C registration to allow for the use of Lorsban in Sweet Potato with a 60 day pre-harvest interval (PHI).

Lorsban is still labeled for pre-plant incorporated application only.