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Eastern New York Field Crops Pest Report, 2004
This is a seasonal scouting report giving growers in the Eastern New York area information on the presence of agricultural pests. The report is written by Ken Wise, IPM Extension Area Educator for Livestock and Field Crops.
August 13, 2004
Winter Wheat, Aphids and Yellow Dwarf Virus
Barely yellow dwarf virus, now know as yellow dwarf virus (YDV) in wheat is a serous disease across the country. This disease is transmitted by several species of aphids that infest wheat. When aphids feed on the plants they infect the wheat with the virus. Winter wheat that is infected in the fall does not show symptoms. Symptoms start to appear mid-spring as yellowing of leaves. One management strategy is to plant wheat after the Hessian fly free date in your region. This can limit the number of aphids entering the fall seeded winter wheat fields. Another management option is to use wheat that is resistant to YDV.
Soybean Aphids are Dinner for Several Predators, Parasites and Fungi
Soybean aphids (SBA) have many predators. Of course we all know by now lady beetles enjoy having a feast on SBA. You might have not known that minute pirate bugs also like to have a main course of SBA. Green lacewing larvae are also effective predators of SBA (Pictures of Predators). The combination of the lady beetles, green lacewing larvae and minute pirate bugs have been reported to control up to 86 percent of SBA in a field (Reference). But of course there is more working against soybean aphids. There are also other insect predators that contribute to SBA reductions. Syrphid fly larvae are good predators of SBA as well as damsel bugs. There are also parasitoids that help control SBA. Parasitoids are little tiny wasps that lay their eggs inside the soybean aphids. Have you ever seen a parasitized aphid? They look like a tan colored mummy in the shape of the aphid (SBA Mummies). It does not stop with insects controlling SBA, there are also fungal pathogens. These fungal pathogens can be effective when populations SBA are high. The disease appears as a yellow to brown fuzzy looking aphid (Picture of Fungal Control of SBA). Under favorable conditions when the relative humidity is high the pathogen can move through a population killing SBAs very quickly.
Leaf Diseases as Compared to Soybean Rust
(Written By Julie Stavisky)
Soybean Rust is attacking soybean crops in the southern hemisphere. It has not yet been reported in the United States but experts warn that it may be only a matter of time. Your first line of defense should be the ability to identify this new pathogen from those that might be common to soybeans grown in New York State. The following are the differences in common foliar diseases of soybeans as compared to soybean rust:
Brown spot (Septoria leaf spot)
Weeds in the Fall!
Weed Presence- Weed Rating Scale:
None: No weeds present
Few: Weeds present but very few plants within the field. Enough plants to produce seed but not enough to cause significant economic loss in the current year.
Common: Plants dispersed throughout the field,
an average of no more than 1 plant per 3 feet (.91m)
Abundant: Fairly uniform concentrations across field. Average concentrations of no more than 1 plant per foot (.30m) of row or scattered spots of severe infestations.
Extreme: More than 1 plant per foot (.30m) of row for broadleaf weeds and 3 plants per foot of row for grasses, or large areas of severe infestations.
So take a few minutes and encourage growers to look at their fields---it will help save on weed control costs and increase crop production. Remember, if you don't look, you will never know. For more information on weeds in corn checkout our online publication: Weeds in Field Corn
Keith Waldron and Julie Stavisky (NYS IPM) for contributing
to this week's report.