In New York State the use of chlorpyrifos (Lorsban-Dow/DuPont) is limited to a single application per season. Two types of applications can be made, either directed to the tree canopy to manage scale, beetles including borers and plum curculio, aphid, lepidopteran and plant bug or Lygus pests, or course trunk spay directed to the lower 4’ of the tree to manage trunk boring pests such as dogwood borer and black stem borer. Lorsban can still be used in NY during 2019-2020.
On April 30th NYS legislators approved Senate bill S5343 and Assembly bill A2477B, which will bring about a ban on chlorpyrifos in New York beginning in 2021. This legislation is part of a larger environmental package and requires the approval of Gov. Andrew Cuomo’s (D) to put the new law into effect. The bill would ban all use of chlorpyrifos except for on apple tree trunks by Jan. 1, 2021 and ban the pesticide altogether by December 2021. The loss of this tool is very unfortunate.
Effective control options for pests managed by chlorpyrifos are available for all but one of the pest complex.
The ambrosia beetle, the black stem borer (BSB), Xylosandrus germanus (Blandford) (Coleoptera: Scolytidae) is the one Asian invasive insect pest for which we have no Lorsban replacement. Finding a solution for BSB prior to the loss of chlorpyrifos by 2021 will be critical to maintain orchard productivity and sustainability.
To date hundreds, possibly thousands of young apple trees have been killed by this one insect pest in orchards throughout the Eastern US tree fruit growing region. (see prior post on this topic)
This BSB is attracted to young apple plantings under environmental or biotic stress. Stress include drought and heavy rain conditions, such as we’ve been experiencing over the past few weeks in the Hudson Valley. During these conditions the tree emits ethanol (ETOH) to which the BSB is highly attractive.
ETOH is an indication of tree stress and reduced defense mechanisms within the tree physiology, leading to greater insect infestation and higher levels of reproductive success.
The female has been flying since 16th April in the Mid-Hudson Valley. It has not yet been observed burrowing into cut bolts of apple wood soaked in ETOH. It can often be found burrowing into apple from bloom through petal fall and into the early season. A second generation occurs during mid-late summer. Given the cool days, BSB beetle activity has been quite low to date.
Trunk applications of Lorsban at petal fall should reduce the boring activity of BSB in water logged orchard sites with heavy soil and newly planted apple. Other pest management options include Danitol 2.4EC at 16-21.3 fl.oz./A or Warrior II 2.08CS at 2.56 fl oz/100 gal water. Frequent applications may be required using the pyrethroid class of insecticides.