Tuesday, May 29, 2012

Growing Season Moving Along Without Any Big Hiccups

Haystacks are being collected.

Second cutting of  alfalfa is complete.
While the weather has been a little unpredictable this spring, the growing season has been rather predictable in 2012. So far, there have been no major surprises.

Spider mites are starting to increase.
- UC IPM photo 
Around the Valley, alfalfa growers have wrapped up their second cutting without a hitch. On the pest front, I’ve been seeing an increase in alfalfa loopers. These bugs show up in May and early June and feed on the leaves. However, loopers are seldom a threat because they are usually kept in check by natural enemies. In fact, there has been a good increase in beneficial insects, including lots of big-eyed bugs and minute bugs as well as green lacewings.

Aphids also seem to be under control. Growers are timing their cutting to control this pest. By timing the cutting when aphids are on the rise, you end up getting rid of an entire generation of aphids.

Alfalfa loopers usually aren't a threat.
- UC IPM photo
During my visits to cotton fields, I am noticing issues with spider mites, which can suck out the cell content from leaves. Some growers are mulling over the idea of treating for mites based on their earlier assessments in the field. However, I suggest growers do another check of their fields before going ahead and treating for the pests. You might find the beneficials such as minute pirate bugs and big-eyed bugs are providing adequate biological controls to reduce the infestation and saving the expense of treatment.

Minute pirate bug  is a good bug.
For example, the infestation might have been 25 percent during a previous field check. If you go out again just before applying materials, the infestation may be down to 6 to 7 percent thanks to beneficial insects keeping them under control. You want to avoid “revenge treatment.” Translated: You may gain a certain amount of personal satisfaction from treating the field, but the move may not give you an economic return because the pests have moved on.

So before going ahead with treatment, check with your pest control advisor and take a closer look at the plants by doing leaf counts for mites.

Field Day Alert:  Don't miss our June 12 Cotton Field Day featuring UC IPM advisor Dr. Pete Goodell and UCCE Fresno County cotton specialist Dan Munk. They will offer valuable tips for early season pest and agronomic management during the 10 a.m. to noon event at the Housley and Vandenberg Farm on Sierra Avenue in Firebaugh. Directions are available in the events section of the Sustainable Cotton Project’s website – www.sustainablecotton.org.  One and a half hours of continuing education credits have been applied for. Bring your questions and invite a fellow farmer.

Monday, May 21, 2012

Growers Should Manage Pests by Watching Closely

Look what I caught in my sweep net: Thrips and aphids.

The nice weather is good for young cotton plants – and pests too. I’m starting to spot small amounts of spider mites and thrips in the cotton fields as I make my rounds scouting fields across the Valley.

Thrips will feed on leaves and buds and may cause seedlings to become deformed. But the hot weather will help plants grow out of the damage. Growers and UC Integrated Pest Management experts believe thrips do more good than bad because they will prey on mites. For a discussion about this pest, read UC IPM advisor Dr. Pete Goodell’s blog about western flower thrips.  The weekly MiteFax report by Owen Taylor features more information about thrips by UC extension cotton specialist Bob Hutmacher.

One bad bug is the spider mite. The pest can cause leaves to turn yellow or red and fall off. Losing leaves reduces the amount of energy for the plants and may cause squares and bolls not to develop fully and end up dropping to the ground.
Water trucks will keep the dust down.

In the past couple of years, I haven’t seen any major mite outbreaks. I attribute a lot of that to good preventative measures taken by our growers. Dust control, for example, is an important measure to keep mites under wraps. Growers are doing a good job with water trucks wetting down the dirt roads around their fields once or twice a day. Managing dust helps prevent mites living on dusty roads from being disturbed and blown onto plants.

So far, the cotton plants are at second and third true leaf on the westside. In the Dos Palos area, plants seem to be developing faster and are on their third or fourth true leaf.

Overall, by my count, the plant population is ideal to optimal, running from 48,000 plants per acre to 54,000 plants per acre. Growers want to be in the 30,000 to 60,000 per acre plant range.

Fusarium Wilt damages  cotton plant.
During the early season, growers are always worried about diseases affecting the young plants. Fusarium Wilt can be troublesome fungal disease. In mild instances, leaves will wilt and drop, leaving bare stems. Plants will die in the worst case. Some areas are dealing with various Fusarium problems. Check out the UC IPM website to read more about Fusarium Wilt.

This is something growers need to monitor. If they suspect potential problem areas, they should consult their pest control advisors. Also, veteran farm advisor Dan Munk of the Fresno County UC Cooperative Extension is a good resource.

Alfalfa harvesters are busy in the field.
On the alfalfa front, growers are well into the second cutting of their crop. Aphids are coming on strong now. Lygus and lygus nymphs are become prominent as well. With grain crops drying, alfalfa is the only lush plant around for these pests to inhabit.

It’s important now for growers to leave a quarter swaths of uncut alfalfa at the end of each field to prevent aphids and lygus from migrating to cotton fields. I suggest leaving 2 percent of the acreage uncut around the border and center of the fields, if there is a neighboring cotton field. 

I want to wish everyone an enjoyable Memorial Day weekend.

Monday, May 14, 2012

Summer-like Spring Weather is Just Cool with Cotton Growers

Even by San Joaquin Valley standards, the weather has been rather hot for this time of year with our local temperatures surging to near-record highs. With Mother’s Day weekend seeing the mercury approaching triple digits again, this springtime hot spell means ideal weather conditions for young cotton plants.

Leaving strips of uncut  alfalfa is a good IPM practice.
It also is helping the alfalfa crop. Some growers are cutting alfalfa in their fields for the second time this season. The rest should be harvesting soon. In my sweep nets, I am finding an increase of aphids and lygus. It could be an early season for aphids in the cotton fields around the Valley.

Now is the time for alfalfa growers to start making plans for managing these pests and keep them from migrating to nearby cotton fields during the summer. Aphids are troublesome when the cotton bolls start opening.

Here are  young cotton plants at the true leaf stage.
A key Integrated Pest Management strategy involves keeping threatening pests such as lygus and aphids from migrating from alfalfa during cutting to nearby cotton fields. One of the best management practices is leaving strips of uncut alfalfa as habitat to attract natural predators such as green lacewings and parasitic bugs. In mid- to late June, growers should start leaving one 8 to 12-foot wide strip during the third cutting. So far this season, beneficial insects are keeping the aphid populations in check.

Cotton plants per acre are on target.
Throughout the Valley, all the cotton has come out of the ground. The plant population is good. I’m counting 46,000 to 56,000 plants per acre. Generally, the optimal per-acre count is in the 30,000 to 60,000 range.
Plant development is progressing well. Many plants are coming into the true leaf stage. It seems fields in the Dos Palos area are developing a little faster than in the Firebaugh region. Many Dos Palos growers are seeing their plants reach the first node stage.

Six rows of black-eyed beans along a safflower field will
create a natural habitat to keep bad bugs out of cotton.

The natural habitats we planted this season are also looking good. We just finished planting a habitat of six rows of black-eyed beans along a safflower field to keep lygus from going into nearby cotton later this season.
I want to thank all the growers who worked with us to put in the habitats. This extra effort should pay off in the long run as we strive to reduce pesticide use, protect the environment and health of fellow community members and improve crop yields.

Tuesday, May 8, 2012

Ants in the Almond Orchard: Time to Manage This Pest

Long-time almond expert
Walt Bentley offers tips.
Editor’s note: This season, we welcome again our guest blogger UC IPM entomologist Walt Bentley, whose specialty includes managing pests in almonds.

Ant damage to almonds continues to be a difficult problem for farmers to manage. In all areas of the state populations of the three species of ants which cause damage appear to be increasing. From Fresno County going south to Kern County the California fire ant (also called the southern fire ant), Solenopsis xyloni, is the damaging species.

Another, less common species, is the thief ant, Solenopsis molesta, which is slightly smaller than Xyloni. In Merced, Stanislaus, and San Joaquin Counties both the California fire ant and the pavement ant Tetramorium caespitum can be found causing damage. In the Sacramento Valley the pavement ant is the predominant species. 
Pavement ants are predominant in the Sacramento Valley.

Although almond farmers will know, from past history of damage, whether or not they have a problem species in the orchard, there are other species that are considered more beneficial than harmful. These include the bicolored pyramid ant, Doriomyrma bicolor and the native gray ant, Formica aerata. This latter species has been found to actively feed on peach twig borer in unsprayed peach orchards.

The best way to separate the damaging species from those not causing damage is by examining the thin waist between the last pair of legs and the abdomen (stomach). Both the pavement and the California fire ant possess two bumps or nodes while the beneficial species have only one node.  Also, the damaging species will often be found with weeds growing within the nest and are easily excited by disturbing the soil near their nests.  Finally, the pavement, California fire ant, and thief ant will aggressively bite and sting.  The California fire ant sting, in particular, is quite painful.
Look out for the pavement ant.

While control information has applied to all three damaging species, monitoring methods and thresholds were only developed for the California fire ant. This species is considered the most damaging. We do know that feeding on almonds occurs when the nuts are on the ground, after being shaken from the tree.  In only a few instances will ants climb into trees to feed on nuts.  This usually occurs when limbs touch the ground giving ants easy access to hullsplit nuts. 
Learn to identify the California fire ant.

The primary factors that influence damage include the population of ants in the orchard and the length of time the nuts are left on the ground to dry. The longer the nuts are on the ground, the more damage you can expect. And, as you might guess, the greater the population in the orchard the more potential for damage.

Years ago work was done on treatment thresholds for the California fire ant and the damage potential for 3 different population densities is shown in Figure 1. This information is also available in the Almond Pest Management Manual and the Pest Management Guidelines for Almond. 

In general colony counts of 3 or more per 1,000 square feet can lead to damage at harvest, if conditions are right. This is a big if, especially for the California fire ant, because high temperatures (95 degrees Fahrenheit or higher) will restrict their feeding.  If such high temperatures exist while the nuts are drying on the ground, damage from the California fire ant will be minimal.  This is true even for very high populations.  If daily highs are less than 90 degrees, damage can be extensive. The same information is not known for the pavement ant although it appears to behave similarly.
Limit the time nuts are on the ground to avoid ant damage.

There are some cultural management techniques that can be used to keep ant damage to a minimum but be cautious, particularly if navel orangeworm is also a problem. Where ants are the primary pest, leave the almonds on the tree for as much drying as possible.  This will allow you to pick the nuts from the ground without a delay to dry. You can try to schedule the shaking of heavily infested blocks late in the season, again to keep the nuts on the tree for as long as possible. Beware, however, if you have a navel orangeworm problem.  The delayed shaking will increase worm damage.

Ants damage soft shell varieties.
Another point to remember is that only the soft shell varieties, such as Nonpareil, are damaged by ants. Hard shells such as Mission, Butte, Padre and, to some extent Carmel, are not fed upon.  Don’t bother to treat for ants if you have a hard shell orchard. 

Ant baits have been very effective in reducing damage, when applied at the correct time.  These include such products as Esteem©, Clinch© and Extinguish©.  Each requires a specific time interval, prior to shaking, to be applied.  In applying baits, be sure to mow any cover prior to the application. For further information go to the IPM Guidelines for Almonds.

Figure 1.  Projected ant damage to soft shell almonds based on colony number and days left on the orchard floor.

% Damage by Ants to Almonds on Orchard Ground
                                     Days nuts on ground
#  colony entrances
5,000 sq ft in Apr-May






Monday, May 7, 2012

Cotton Season in Full Swing as the Valley's Weather Heats Up

 April showers are history. Triple-digit temperatures will soon be here – possibly as soon as next week. That means cotton season is in full swing. There are only 26 or so weeks until harvest.

Here's a disease-infected seedling.
- UC IPM photo
Around the Valley, cotton seedlings are popping up nicely because of the ideal warm weather we have been experiencing in our Valley.

The germination rate is good. So far, I haven’t heard much about early season disease problems.

In surveying the emerging cotton fields, I’ve seen good stand development. Insects, plant pathogens or poor weather or soil temperatures during planting can cause weak stand establishment. If growers see weak stands, they need to look for any pests by digging around the soil of the damaged plants. Check the University of California Statewide Integrated Pest Management web site for more information about assessing stand establishment.
One of our habitats of  young mustard, corn and sunflowers. 

The natural habitats we planted last month at some of the participating SJSFP fields are progressing well. Already, I’ve seen some of the beneficial insects such as ladybugs around the emerging mustard plants. That bodes well for our effort to use biological controls to keep crop-damaging pests at bay and reduce the use of pesticides.

Keep a close watch for lygus.
- UC IPM photo
Around the alfalfa fields, growers have wrapped up irrigating their crop. They’re almost ready for the second cutting. I’ve seeing aphids and lygus numbers going up. I’m suggesting growers continue to monitor these pests. So far, the early season is looking good.