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Archive for the ‘Pesticides’ Category

 

Broad mites in ornamental crops – Part 1: Challenges and treatments

Broad mites can be controlled using insecticides or biological control.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

 

Western flower thrips and aphids have long been the most challenging insect pests in greenhouses. More recently, broad mites (Photo 1) have been posing a more serious threat for greenhouse growers. Broad mites are a potential threat to some of the most important Michigan floriculture crops. According to my previous article, “Attention scouts: Crops that are insect “magnets” in the greenhouse,” the top 10 plants that are attractive to broad mites are New Guinea impatiens (Photo 2), zonal geraniums, Thunbergia, Torenia, verbena, Rieger begonias, Scaevola, angel wing begonias, ivy geranium and buddleia.

So, why are broad mites so concerning? Broad mites are concerning because they are microscopic and are very difficult to see with the common 5x to 10x hand lens. You must send samples to a diagnostic lab or contact your local Michigan State University Extension floriculture educator for a positive diagnosis.

In addition, greenhouse scouts and growers usually notice the plant damage after the populations are already very high and the crops are unsalable. Often times, the damage to the upper leaves near the apical meristem is only noticeable 20 to 30 days after they began infesting the crop.

The greatest populations of broad mites when scouting crops are often not on the plants with the greatest amount of damage. By the time the damage is significant, broad mites have moved on to the neighboring plants with “fresh, new, tasty” tissue. Therefore, greenhouse scouts should actually sample the plants adjacent to those with heavy feeding damage.

broad mite damage

Photo 2. Broad mite damage on New Guinea Impatiens. Photo by Heidi Lindberg, MSU Extension.

The following products are recommendedfor broad mites: Avid, Akari, Judo, Pylon, SanMite, and 2% horticultural oil. For growers interested in using biological control, the predatory mite, Amblyseius swirskii (Photo 3), has been shown to be effective against broad mites. However, cuttings and propagules must be free of pesticide residue in order to effectively use biological control for broad mites. Contact your young plant or cutting supplier to learn about the plant’s pesticide history.

a. swirskii

Photo 3. Amblyseius swirskii. Photo by Evergreen Growers Supply.

One study in Belgium showed that using A. swirskii is actually more effective than the standard chemical treatment (Abamectin) in Belgium. When researchers released broad mites (P. latus) on Rhododendron plants, all of the following treatments were more effective than the weekly abamectin spray:

  • Three weekly releases of A. swirskii beginning in April
  • One release of A. swirskii during April
  • One release of A. swirskii during May
  • One release of A. swirskii with the additional food source Artemia during April
  • One release of A. swirskii with the additional food source Artemia during May

Greenhouse growers who are not getting adequate control of broad mites may want to consider a weekly release of A. swirskii. Contact your local biological control specialist or consultant to develop a strategy for preventative broad mite control.

For more information on the location of broad mites in the crop and about an intensive sampling program, read “Broad mites in ornamental crops – Part 2: Scouting and sampling.

The study referenced in this article is: Gobin, B., E. Pauwels, E. Mechant, and J. Audenaert. 2017. Integrated control of broad mites in ornamental plants under variable greenhouse conditions. IOBC-WPRS Bulletin Vol. 124: 125-130.

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How Kenya is soldiering on in war against armyworms – Daily Nation

The good, bad and ugly in fight against armyworms

Friday May 12 2017

Patrick Wanjala, a maize farmer in Namanjalala, Trans Nzoia County displays a maize plant attacked by armyworm in his farm.

Patrick Wanjala, a maize farmer in Namanjalala, Trans Nzoia County displays a maize plant attacked by armyworm in his farm. The pest has potential of causing famine since the larva not only feeds on staple food crops but also grass, pasture and any green vegetation. PHOTO | JARED NYATAYA | NATION MEDIA GROUP 

By STANLEY KIMUGE
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From far, Malaki village, about some 6km from Kitale town in Kwanza in Trans Nzoia County, is lush green, with farms teeming with the maize crop. Nothing looks unusual at various fields but as one moves closer to the maize farms, a different story unravels.

The maize crop has been ravaged extensively by the fall armyworms, with the area being the worst affected by the pests.

Patrick Wanjala, a maize and beans farmer, bends for the umpteenth time looking at his crop. His face is forlorn showing the anguish and frustration that the pest has caused him.

“I have never seen anything like this before in my life as a farmer. I am not sure if I will harvest any maize this season.”

Under normal circumstances, he would have harvested between 60 and 70 90kg bags from his one-and-half-acres.

“It started with small holes on the plants’ leaves and I thought it was just the stem borer as that is the common pest here. I sprayed but nothing changed then reports of the armyworms having invaded the region filtered in,” recounts Wanjala.

In a bid to tame the notorious pest, Wanjala said he applied ash and even red soil as desperation set in.

“I tried that hoping that it would work but it was all in vain,” says Wanjala, whose crop was attacked some two months ago.

Then hope came when the government announced that it was coming up with measures to tackle the pest that is a threat to food security since it is destroying maize.

Armyworm has potential of causing famine since the larva not only feeds on staple food crops (maize, wheat, millets and sorghum) but also grass, pasture and any green vegetation mainly on the leaf lamina, leaving only the mid-rib

A team was set up at the county and national level to co-ordinate the fight against the worms.

But to date, Wanjala says he has not received any chemicals from either the county or national government as promised.

“I have been to the county offices several times hoping to get chemicals in vain. Two days ago I went there. More than 2,000 of us had turned up and the chemicals were not enough despite the little amounts they were giving,” says Wanjala, who is yet to spray any chemicals on his maize crop.

ONGOING RAINS

So far, according to the county government, some 15,000 acres of maize have been affected in the region, but the inspection of the fields is ongoing to ascertain exact figure.

The ravenous pest has fed on the “heart” of most of plants leading to stunted growth.

Trans Nzoia County, which is the country’s food basket has borne the brunt of the armyworm attack, with an estimated thousands acres of maize having been ravaged.

County’s chief agriculture officer Mary Nzomo says the county is distributing chemicals to farmers to contain the situation, though they are not enough.

“We have been able to spray about 10,000 acres out of the over 15,000 affected by the pest,” says Nzomo, noting an adult worm lays up to 2,000 eggs and it’s important to kill them before they become adults to avoid spreading. Besides spraying, she says the county has taken other measures to curb spread, which include sensitisation of farmers.

Maize crop attacked by the pest in a farm.

Maize crop attacked by the pest in a farm. Normally, the pests feed in the evenings and early morning. PHOTO | JARED NYATAYA | NATION MEDIA GROUP

“We are holding public barazas where we also distribute educational flyers and we do on-farm demonstrations. We are currently holding talks on FM radios as well as print and broadcast media to spread the message,” she says.

She notes despite promise by the national government that they will get chemicals since it recommended the spraying be done three times, no pesticides have been distributed to them and in the nearby Uasin Gishu County.

“Those farmers that have sprayed have noticed the chemicals are working. What we are telling farmers is that if you spot the pest in your area, you need to spray all maize plants including those that have not been attacked to avoid re-infestation,” says Nzomo.

Other factors are also hampering the struggle to eradicate the pest including the rains.

“Sunny and humid conditions help control multiplication of the pest but with the ongoing rains, it becomes a challenge to spray. Normally, the pests feed in the evenings and early morning and this is the time we are asking farmers to spray, but with the heavy rains, when they spray the chemicals are washed away.”

The farmers have been advised to spray at least three times in two weeks after germination, when the crops are knee-high and during the formation of the tarsals (about the flowering stage) to control the pest.

SALVAGE CROPS

Last month, Trans Nzoia set aside Sh45 million while Uasin Gishu Sh2 million to fight the pest.

“This was to cover about 20 per cent of farmers, mainly small-scale. On average, the cost of spraying is about Sh2,000 per acre but we are assisting to do one spraying for farmers,” says Nzomo.

Joseph Cheboi, Uasin Gishu County Director of Agriculture, says that four out of six sub counties have reported armyworm infestation, with Soy and Moiben that border Trans Nzoia County being worst hit.

Bernard Kimuiguei, a farmer in Kipsombe in Soy, says that his 20 out of 40 acres under maize has been affected.

“I was given some chemicals by the county officials but they were too little. I have to dig deeper into my pockets and it is really costly,” he says.

Dr Victoria Tarus, county chief officer in-charge of agriculture, says approximately 600 acres have been infested but they are distributing chemicals to farmers.

Robert Aluda, a farmer in Namanjalala Trans Nzoia, says besides the failure to get pesticides, lack of information on how to control the pest is also the biggest setback.

Trans Nzoia County Deputy Governor Stanley Tarus, Agriculture Chief Officer in the county Mary Nzomo and farmers during the launch of Fall Armyworm Management Campaign

Trans Nzoia County Deputy Governor Stanley Tarus, Agriculture Chief Officer in the county Mary Nzomo and farmers during the launch of Fall Armyworm Management Campaign in the county on May 09, 2017. Farmers whose maize crop had been infested were given pesticides to fight the invasion. PHOTO | JARED NYATAYA | NATION MEDIA GROUP

“If we knew from the beginning what the pest was and how to eradicate it, we would have salvaged our crops. We just heard on the radio that a pest had crossed the Kenya-Uganda border but we thought it won’t be that destructive so we did not act fast,” says Aluda, who took a bank loan of Sh50,000 and sank into the maize farm.

But it is not all gloom. Charles Sawe from Moiben says he bought himself chemicals recommended by agricultural extension officers and he has been able to clear the worms on his expansive farm.

He says that only few farmers have received the government chemicals.

UNDER CONTROL

The government recommended the following chemicals; Duduthrin, Twigapyrifos, Belt, Match, Ranger, Loyalty, Integra, Orthene, Jackpot, Imaxi. They are also using cocktails and are working well.

Other chemicals include Chlorpyrfos, Alpha Cypermerthrin , Indoxarb, Di Ubenzuron, Clorantraniliprole and Spinetoram.

At the Coast, where there was African armyworm attack, farmers have reported success in eradication of the pest. In Taita Taveta County, the armyworms invaded Njukini and Challa within the agriculturally rich Kasigau-Maktau belt and some parts of Mwatate.

Agriculture chief officer Evans Mbinga said the worms invaded 25 hectares under maize crop as well as some ranches. “At least 60 farmers were affected by the armyworms invasion, which followed rains after a prolonged drought. Following the rains, new grass sprang up and it created a conducive environment for the armyworms to multiply,” he explains.

The agriculture official says the county has brought the armyworm invasion under control after spraying pesticides on affected farms. “County field officers teamed up with farmers in spraying the pesticide known as Cypermetherin which wiped off the armyworms.”

Joseph Ivuso, a farmer in Taita, whose 2.5 acres of maize were invaded says he eradicated the pest with the help of county agricultural officers.

In Kwale County, the director of agriculture David Wanjala says the armyworms invaded 25 acres of maize in Lunga Lunga.

However, he noted that the pests did not cause a big damage. “When the farmers planted maize, the moths were at pupae stage in the soil, so when the rains started pounding the region they easily drowned.”

But despite the rains wiping away the pests, Wanjala says the county is expected to receive 1,000 litres of pesticide from the national government next week, which would be used in case the worms reappear.

Additional reporting by Mathias Ringa

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IPM approach best for soybean aphids | Ohio Ag Net | Ohio’s Country Journal

About 89.5 million acres of soybeans will be planted across the United States in 2017 — a record high, according to the USDA. Research published in the April 2017 issue of Pest Management Science indicates that many of these soybean growers will invest in neonicotinoid insecticide seed treatments. The two-year, multi-state study revealed that, even during periods of infestation by the soybean aphid, the neonicotinoid treatment produced the same yields as using no insecticide at all.

The study was a joint effort of Purdue University, Iowa State University, Kansas State University, North Dakota State University, the University of Minnesota, South Dakota State University, and the University of Wisconsin. The research was grower-funded, using soybean checkoff funds provided by the North Central Soybean Research Program (NCSRP).

The neonicotinoid insecticide thiamethoxam, which is applied as a coating to soybean seeds, provides a maximum of two weeks of protection against insect feeding. Aphids typically don’t reach damaging numbers until much later in the season, said Christian Krupke, an entomology professor and extension specialist at Purdue University and one of the researchers and authors of the study. As a result, when soybean aphid populations reached threshold levels, from late July to August, the insecticide levels in tissues of neonicotinoid-treated soybean foliage were similar to plants grown from seeds without the insecticide.

Bruce Potter, Insect Pest Management (IPM) specialist for the University of Minnesota Extension, said one of the most important aspects of the study was providing soybean growers information about how to invest their funds.

Potter said soybean growers in northern regions, including Minnesota, don’t have chronic and consistent economic infestations of early season insect pests.

“Farmers wouldn’t get an advantage from putting insecticide on soybean seeds,” he said. The exception to this conclusion would be fields at a higher risk for infrequent pests like seed corn maggot and white grub or for seed production fields where bean leaf beetle and bean pod mottle virus occur. The research study concluded soybean farmers in all the regions in the study should employ the IPM approach, combining scouting and foliage-applied insecticide where necessary.

“In terms of long-term sustainability and the bottom line for your yearly balance sheet, the IPM approach is the most effective approach for pest management in the growing season,” Krupke said.

A study examining neonicotinoid seed treatments of corn had a similar result. This study, published in the journal PLOS ONE in March 2017, was conducted by Krupke’s doctoral student, Adam Alford. It revealed that concentrations of the insecticide most commonly applied to corn seeds, clothianidin, declined rapidly and approached zero in plant tissues within 20 days after planting. Less than 5% of what was applied to the seed was recovered from corn plants in the field.

Currently, at least one of two neonicotinoids, clothianidin or thiamethoxam, are routinely applied to more than 80% of the corn and over half of the soybeans grown in North America.

Previous studies, although smaller in size, had shown similar results with neonicotinoid seed treatments, which were introduced in the 1990s, said Kelley J. Tilmon, state extension specialist for the Ohio Agricultural Research and Development Center and an associate professor of entomology at Ohio State University. She performed the research in South Dakota when she was on the faculty of South Dakota State University.

The recent study was launched to provide more definitive scientific answers across a large geographic area, Tilmon said.

Janet J. Knodel, extension entomologist and associate professor at North Dakota State University, said the results were similar in North Dakota.

“As part of our research, we saw the soybean aphids coming into the field in late July and early August in North Dakota,” she said. “By then, the residual of the insecticide seed treatment is gone.”

Farmers can consult with their local university Extension services for additional information on specific pest management strategies in their state. They also can obtain information by downloading the Purdue Extension publication “The Effectiveness of Neonicotinoid Seed Treatments in Soybean” at http://bit.ly/2pZ8IBi.

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SW FarmPress

In new study, researchers say agriculture can be important to honey bees


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Honey Bee
A new study indicates that agricutural production may be beneficial to honey bees, but care must be taken with pesticide selection and application.
Scientists at the University of Tennessee Institute of Agriculture published results of the study in a recent issue of the Journal of Economic Entomology, titled the “Agricultural Landscape and Pesticide Effects on Honey Bee Biological Traits.” While not all news is good news according to the results of the study, some interesting discoveries were made.

Logan Hawkes 3 | May 09, 2017

It’s no secret that pesticides can cause harm to honey bee colonies, but a new study from University of Tennessee researchers has found that  under the right conditions, the overall health of honey bee colonies can benefit as a result of row crop production.

The number of honey bee colonies in the United States has declined by 45 percent over the past 60 years, not just because of agrochemical exposure, but also a result of various pathogens, parasites, and other factors such as changing farm demographics. The new study illustrates that while some aspects of farming represent a high risk for honey bee colonies, a determination that row crop farming can contribute to the well being of bee colonies is encouraging news to the agricultural industry.

Scientists at the University of Tennessee Institute of Agriculture published results of the study in a recent issue of the Journal of Economic Entomology, titled the “Agricultural

Landscape and Pesticide Effects on Honey Bee Biological Traits.” While not all news is good news according to the results of the study, some interesting discoveries were made.With little argument, results of the study concede that pesticides are thought to be a principal factor causing honey bee decline, in addition to damages caused by the parasitic varroa mite. Many insecticides are toxic to bees, even at very low doses, and they may cause significant disorders at sub lethal doses in colony dynamics and the division of labor of honey bee colonies by affecting honey bee behavior, orientation, communication, and return flights.

ENVIRONMENTAL FACTORS

In addition to harmful pesticides, however, the study indicates some environmental factors play a central role in colony losses, such as habitat loss or changes, poor nutrition, inadequate foraging flora, and the transportation stress induced by the excessive “transhumance of honey bee colonies to provide pollination services.”

While pesticides are necessary for pest control in agriculture, increasing crop production and providing worldwide food security, care must be taken by farmers to minimize that damage through adequate control measures, a practice that row crop farmers have been making an effort to adopt in recent times. Those efforts are helping to reduce the negative aspect of pesticides, more precisely neonicotinoid class pesticides, and their capability of suppressing honey bee immune-competence that might lead to an impaired disease resistance capacity.

For the purposes of this study, a number of locations were utilized to test the effects of landscapes (urban versus agricultural) on colony health. Researchers measured three key elements of honey bee colony health—colony weight, brood production, and colony thermoregulation—in different landscapes and with different risks of pesticide exposure. Researchers then evaluated honey bee colony performance in replicated exposure groups in an effort to tease apart the relative effects of pesticides and environment on colony health.

The results indicated a number of factors. While additional external elements influenced colony weight and brood production, it was determined that hives in agricultural areas did exhibit better colony weight as a result of better forage opportunities. The cause of death among colonies varied depending on location, but it should be noted that pesticide exposure was accountable for pollinator death in colonies located near high production agricultural areas.

NUTRITION FACTOR

In conclusion, the study indicated honey bee colonies foraging in moderate and high production areas where row crop farming was practiced were clearly able to grow faster and to a larger size as a result of better access to sustainable nutrition sources than bees foraging in more urbanized areas. Better nutrition sources and nectar yields in farm areas helped to develop greater population size, which in turn enabled better colony thermoregulation.

The study further concludes that while non-farm areas may provide a less-toxic environment for honey bees, they may not provide sustainable foraging resources, leading to colony starvation. Thus, a trade-off appears to exist between increased food resources and the potential for exposure to pesticides in agricultural systems. Careful selection of pesticides and conscientious application of bee-toxic pesticides, however, should greatly reduce the risk of honey bee exposure and promote healthier hives under the right conditions.

Access the full article here.

( https://academic.oup.com/jee/article-abstract/doi/10.1093/jee/tox111/3231574/Agricultural-Landscape-and-Pesticide-Effects-on?redirectedFrom=fulltext )

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The Australian Government’s Department of Agriculture and Water Resources has released an Industry Advice Notice (IAN) advising that New Zealand has suspended imports of Australian rockmelons and honeydew melons that have been treated with dimethoate. This suspension is effective immediately.

Summary of changes and key points:

  • The New Zealand National Plant Protection Organisation has advised that, effective immediately, they will no longer be accepting consignments of rockmelons or honeydew melons that have been treated with dimethoate.
  • The suspension includes consignments that are currently in transit.
  • The department will not be issuing certification with EXDOC endorsement 1646 for rockmelons or EXDOC endorsement 3576 for honeydew melons.
  • Exports sourced from pest-free areas are still permitted.

source: foodprocessing.com.au

Publication date: 4/12/2017

 

 

 

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MIT Technology Review, Vol 119, No. 6, (MIT News Section, page 6).

Spray That Stays

When farmers spray their fields with pesticides or orange growers spray water on their crops to prevent frost damage, only about 2 percent of the spray sticks to the plants. The rest of the droplets either bounce right back off the leaves or get blown away by the wind. All that waste costs money and, in the case of pesticide application, contributes to pollution of waterways and exposes farmers unnecessarily to hazardous chemicals. But a team of MIT researchers has found a way to fix that.

A clever combination of inexpensive additives allowed the researchers, led by associate professor of mechanical engineering Kripa Varanasi and grad student Maher Damak, to drastically cut down on the amount of liquid that bounces off, potentially making it possible to use just one-tenth as much pesticide or other spray as would otherwise be needed.

Previous attempts to reduce this droplet bounce rate have relied on additives such as surfactants, soaplike chemicals that reduce the surface tension of the droplets and cause them to spread more. But tests have shown that this yields only a small improvement; the speedy droplets bounce off while the surface tension is still changing, and the surfactants cause the spray to form smaller droplets that are more easily blown away.

The new approach uses two different kinds of polymer additives, each added to a separate portion of the spray. One gives its part of the solution a negative electric charge; the other causes a positive charge. When two of the oppositely charged droplets meet on a leaf, they form a hydrophilic (water-attracting) “defect” that sticks to the surface and makes other droplets more likely to adhere.

The project was developed in collaboration with the MIT Tata Center for Technology and Design, which aims to develop technologies that can benefit communities in India and throughout the developing world. Spraying of pesticides there is typically done manually with tanks carried on farmers’ backs, and since the cost of pesticides can be a significant part of a farmer’s budget, reducing the amount that’s wasted could improve the overall economics of small-scale farming. It could also reduce soil and water pollution and spare farmers excessive exposure to the spray chemicals. And for those spraying water, limiting the waste of often-limited freshwater resources can be significant.

“We can use normal sprayers, with two tanks at a time, and add one material to one tank and the oppositely charged material to the other,” Damak says. The farmer “would do everything as usual, just adding our solutions.”

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west f p

Almond Bloom
The four main fungal diseases in almonds, which can do the most damage to the crop, are brown rot, anthracnose, shot hole, and jacket rot. All four are different and have different sensitivities to fungicides.

Cecilia Parsons | Mar 01, 2017

Warm and wet weather as the Central Valley’s almond orchards burst into bloom makes widespread fungal diseases almost a sure bet.

“If growers get behind on their control and can’t get the fungicide sprays on, they might get hammered this year,” warns Dani Lightle, University of California Cooperative Extension (UCCE) farm advisor in the Northern California counties of Glenn, Butte, and Tehama.

Lightle says, “If pathogens get a foothold and it rains through bloom and after, there may be a lot of crop damage. You can’t catch up with these diseases.”

David Doll, UCCE farm advisor at Merced County, says fungicide applications are a preventative measure, not a control. Wet conditions during this year’s bloom created a perfect environment for fungal growth.

The pathogens are always present in an orchard, Doll explains, but they need a host and the right environmental conditions. Continued warm and wet conditions during bloom can open the doors for fungal infections.

“With no fungicide applications and current conditions, significant yield losses can be expected,” Doll said. “Depending on the variety, it could be 20-30 percent.”

On Feb. 1, the California Department of Pesticide Regulation approved the aerial application of fungicides in six North State counties due to the number of almond orchards inaccessible with ground spray rigs.

The exemption allows for fungicide applications in orchards with standing water. No pumping of water is allowed after the applications and the sprays must cease if a rain event is imminent.

The four main fungal diseases in almonds, which can do the most damage to the crop, are brown rot, anthracnose, shot hole, and jacket rot. All four are different and have different sensitivities to fungicides, according to Doll.

ANTHRACNOSE

Anthracnose symptoms include blossom blight and fruit infections often with spur and limb dieback. Infected flowers appear similar to brown rot strikes. Infected nuts show round, orange-colored sunken lesions on the hull with symptoms appearing about three weeks after petal fall. Nuts can be infected later in the season if conditions are favorable.

Diseased nuts become mummified but remain attached to the spur. Shoots or branches with infected nuts often die. UC Integrated Pest Management (IPM) guidelines report that all cultivars are susceptible.

Management calls for fungicide treatments beginning at 5-10 percent bloom and repeated every 10-14 days if wet weather persists. Specific materials and application rates can be found on the IPM web site.

BROWN ROT

Almond blossoms are most susceptible to brown rot when fully open. Stigma, anthers, and petals are all susceptible to brown rot infection. Gum may secrete from the base of infected flowers.

This fungus survives on twig cankers and on remaining diseased flower parts and spurs. Spores are airborne or water splashed, and infections spread rapidly in wet weather with temperatures in the mid-70s.

Timing for control should be determined by the bloom of the most seriously affected cultivar. If infections were widespread the previous year, multiple fungicide applications may be necessary.

SHOT HOLE

Symptoms of shot hole include spots on leaves, hulls, twigs, and flowers. Leaf lesions begin as tiny reddish specks. Spots on young leaves will fall out leaving a shot hole appearance. Older leaves retain the lesions.

Heavy infections can cause nutlets to drop, become distorted, or gum up. Infected trees will weaken, defoliate, and lose production.

There is a high risk of shot hole development in the spring if shot hole lesions with fruiting structures are found on leaves in the fall. Fruiting structures appear in the center of leaf lesions as small black spots, viewable with a hand lens.

Fungicide applications depend on weather conditions and the level of infection found in the fall.

JACKET ROT

Jacket rot, or green fruit rot, begins later in the bloom period when the fungus infects petals and anthers. The infection can spread to floral tubes or flower jackets causing them to wither and stick to developing nutlets. Entire nut clusters can rot if covered with the infected flower parts.

Jacket rot is not as prevalent as the three other fungal diseases and is more likely to appear in cooler weather conditions. Fungicide should be applied at full bloom to prevent jacket rot.

Lightle says targeting fungicide choices to the fungal disease of concern is vital. She encouraged use of the fungicide efficacy tables available at http://ipm.ucanr.edu/PMG/r3902111.html.

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