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Sugarcane Aphid Monitoring Network

Posted on by Sharon Schroll

——-by  Brian McCornack, Wendy Johnson, Jeff Whitworth, J.P. Michaud, Sarah Zukoff

 

Kansas State University is leading a Sugarcane Aphid Monitoring Network comprised of researchers across the Southern half of the US. This group effort results in a national reporting and mapping of aphid distribution in real-time during the growing season using the online Extension program, myFields.info.

 

In general, migrating populations of sugarcane aphid disperse north from Southern Texas and northern Mexico into Oklahoma and then Kansas depending on weather patterns, temperature, and potential factors limiting aphid population growth, including natural enemies and use of resistant sorghum hybrids. No overwintering in Oklahoma and Kansas has been reported due to a lack of host plants (i.e. grain sorghum and green Johnsongrass) during winter months. Real-time tracking of migrating populations of sugarcane aphid into Kansas results in early detection of this pest for local farmers, which is necessary for timely applications of insecticide, a primary practice for protecting sorghum crops. See our Scouting Card (see picture below) for more management information.

The first observation of sugarcane aphid occurring in production sorghum this season was in southern Texas on March 28, which is not unusual. Colleagues in Texas have indicated that overall aphid presence and population levels at this time are sparse in comparison to previous years. By April 19, SCA was detected only several counties (see picture below) north of the initial report, suggesting that northern movement could progress much slower than past seasons, even in regions where these aphids are known to overwinter on Johnsongrass. As we wait to see how northern migration of SCA plays out, you can plan your management strategy by reviewing current recommendations using the following link to myFields.info: https://www.myfields.info/pests/sugarcane-aphid. In addition, create a free account on myFields.info and be automatically signed up for state- and county-level email alerts when SCA is detected in your area. Furthermore, localized alerts will include contact information for Extension support in your area.

Future monitoring group efforts will include the release of a threshold-based sampling plan for help in making management decisions for SCA, improved mapping features for displaying the change in aphid distribution over time, and mapping the predicted movement of SCA before it happens to help inform farmers.

Alfalfa Update

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

 

Alfalfa weevil populations in north central Kansas seem to be developing as expected.  Fields sampled this week that had not yet been treated had greatly reduced foliage and were showing obvious signs of significant larval feeding, especially compared to fields that had been treated.

 

 

The good news is that the treated fields seem to be doing well and the untreated fields will probably only continue to be seriously impacted for about another week.  Weevil populations are predominately pupae, pre-pupae, or mature larvae which should cease feeding in the next few days.

 

 

This should give the alfalfa a chance to recover.  However, in untreated fields, and even fields that were treated later, after a majority of the larvae pupated, may have some adult feeding, as they may remain in fields until the 1st cutting or until temperatures start getting into the higher 80’s °F.  Adults feed a little on foliage and/or may cause ‘barking’ on stems, but this usually doesn’t stress plants too much unless there are significant numbers of adults.

 

Very few aphids were detected, but there were a few so periodical sampling should continue to ensure that these aphid populations remain at insignificant levels.

 

Sorghum Pests Update

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Double cropped sorghum may still have some ragworm feeding during the whorl stage (see photo).  In addition, there will probably be at least one more generation of headworms and thus later planted sorghum needs to be monitored for headworms between flowering and soft dough when it is vulnerable.  Also, continue monitoring for aphids as there still seems to be a pretty good mixture of greenbugs, corn leaf, yellow sugarcane, and sugarcane aphids.  Some of the fields treated for headworms have reduced numbers of beneficials so they may not be there in sufficient numbers to help control these aphids.  However, some of the fields sampled this week that were sprayed for headworms at least 2 weeks ago had pretty good populations of beneficials already building back up.

sorghum headwormsfall armyworm_sorghum

 

 

Sorghum Pest Update

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

The situation seems about the same throughout north central Kansas with regard to insect pests.  Still finding mixed populations of aphids (greenbugs, corn leaf, yellow sugarcane, and sugarcane) but beneficial insect populations (mainly green lacewings, lady beetles, parasitic wasps, and occasionally syrphid fly larvae) still remain plentiful.  Headworms are also plentiful in just about every field that is not yet at soft dough.  Remember, expect 5% loss/worm/head between flowering and soft dough.  Chinch bugs, both adults and nymphs, are also plentiful at the base of most plants but can also be found feeding on young developing berries in the heads.

Spirea Aphid: Watch out for this “Sucking” Insect

Posted on by Jena Ernsting

–by Dr. Raymond Cloyd

Spirea aphid (Aphis spiraecola) is present feeding on spirea (Spiraea spp.) plants in landscapes. Spirea aphid colonies aggregate on terminal growth (Figures 1 and 2) and their feeding causes leaf curling and stunted plant growth. Spirea aphids prefer to feed on stems and leaf undersides of succulent plant growth. All mature aphids are parthenogenic (reproduce without mating) with females giving birth to live nymphs, which themselves are females. Eggs are laid on bark or on buds in the fall by wingless females after having mated with males. Eggs hatch in spring, and young nymphs develop into stem mothers that are wingless. Spirea aphid females are pear-shaped and bright yellow-green. Stem mothers reach maturity in about 20 days. Each spirea aphid female can produce up to 80 offspring or young females.

Figure 2. SpireaAphidsAggregatingonTerminalGrowthofSpireaPlant
Figure 1: Spirea Aphids Feeding on Spirea Plant

Figure 2. SpireaAphidsAggregatingonTerminalGrowthofSpireaPlant
Figure 2: Spirea Aphids Aggregation on Terminal Growth of Spirea Plant

Although the aphids produce honeydew (sticky, clear liquid); continual rainfall will wash the honeydew off plants. In the summer, both winged and non-winged aphids may be present. The winged forms usually appear when conditions become crowded on infested plants, in which they migrate to a more suitable food source, such as another spirea plant to start another colony. Heavy rainfall and strong winds will dislodge spirea aphid populations from plants onto the ground, where they eventually die. Frequent applications (twice per week) of forceful water sprays will quickly remove spirea aphid populations without disturbing natural enemies such as parasitoids and predators. They have a number of natural enemies including: ladybird beetles, green lacewings, and hover flies that may help to regulate spirea aphid populations.

Spirea aphids are, in general, exposed to regular applications of pesticides such as insecticidal soaps (potassium salts of fatty acids) and/or horticultural oils (petroleum, mineral, or neem-based) that may be effective in suppressing populations of spirea aphid. These pesticides have contact activity only, so thorough coverage of all plant parts is important. Furthermore, these pesticides are generally less harmful to natural enemies compared to conventional pesticides.