Allium Leaf Miner (ALM)

Many weather stations in southern and central counties have exceeded 250 growing degree days (GDD) base 39˚F within the past week.  39˚F is close to the lower developmental temperature (38.3˚ F) which our colleagues at Penn State recommend for predicting the first emergence of ALM adults.  Last year, initial feeding/egg laying scars were detected within a few days of local weather stations recording the 250 GDD threshold.  Limited inspections (Hunterdon, Morris counties) have not revealed scars yet, but feeding and egg laying is sure to come with the next series of warmer days.   Growers in southern counties may reasonably assume there is ALM activity in their area currently.

Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion

Growers should consider initiating the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.  Look for neat rows of white spots descending from the upper tips of allium leaves (see photo at left).  Initial injury often occurs on the tallest leaves.  Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adult at lower right).

Floating row covers, kept on until this flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom), the diamide Exirel (section 2ee recommendation) and the insect growth regulator Trigard are labeled for miner control.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should prepare to respond to the first adult generation.  We will deploy yellow sticky cards and attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.

Allium Leaf Miner

Allium leaf miner (ALM) feeding/egg laying scars continue to increase in chive plantings near Milford, Hunterdon County and Lawrenceville, Mercer County as of this Tuesday.  Chives in home gardens in central Morris County and southern Cape May County were also found to be infested this past weekend, with adults actively flying in plants.  The first (spring) flight of these flies appears well underway.  Yellow sticky cards have captured low, but consistent (range 1-5/card/week) numbers of adults in Hunterdon and Mercer County plantings.  Foliar insecticide applications temporarily suppress catches on the cards.  Growers throughout the state should assume there is egg laying activity in their area currently.

Growers should consider initiating (continuing) the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.  Look for neat rows of white spots descending from the upper tips of allium leaves (see photo at left).  Initial injury often occurs on the tallest leaves.  Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adults at lower right).  Click on photos to enlarge the images.

Floating row covers, kept on until this flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although weekly sprays have not stopped foliar injury.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom), the diamide Exirel (section 2ee recommendation) and the insect growth regulator Trigard are labeled for  leaf miner control.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should continue to respond to the first adult generation.  We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.

Allium Leaf Miner

Allium leaf miner (ALM) feeding/egg laying scars were detected in a large chive planting near Milford, Hunterdon County on Tuesday of this week.  Feeding was very low (<0.5% of chive clusters), but several adults were observed in the planting.  This indicates that the first (spring) flight of these flies has now begun and damage will increase.  No injury or adults were found in a similar inspection of a commercial chive planting near Lawrenceville (Mercer Co.) on the same day.  Yellow sticky cards were deployed in both locations and will be checked weekly.  We look to identify the peak of the flight in central and northern NJ, as well as the period when the adult population is in decline.  Growers in southern counties should assume there is egg laying activity in their area currently.

Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion

The Milford and Princeton NJ weather stations that are closest to these farms both surpassed 250 growing degree days (GDD) base 39˚F on Monday (4/5).  This GDD base is close to that (38.3˚ F) which our colleagues at Penn State recommend for predicting the first emergence of ALM adults.

Growers should consider initiating the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.  Look for neat rows of white spots descending from the upper tips of allium leaves (see photo at left).  Initial injury often occurs on the tallest leaves.  Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adult at lower right).

Floating row covers, kept on until this flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should respond to the first adult generation.  We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.

Allium Leaf Miner

Allium leaf miner (ALM) adults were captured in higher numbers (16/week) on yellow cards in Princeton (Mercer Co.), NJ on Tuesday of this week, while lower numbers (2) were found near Milford, Hunterdon County.  Additionally, a garlic field near Asbury on the Warren/Hunterdon border was found to have 64% of plants exhibiting feeding/egglaying scars.  This indicates that the first (spring) flight of these flies is now in full swing, and damage is ongoing.  ALM flies were observed on foliage in all fields that were inspected this week.

Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion

Growers should consider implementing the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.

Floating row covers, kept on until this flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior),  neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.  The diamide, Exirel, is permitted in NJ under a 2ee label as well.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should respond to the first adult generation.  We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.

Allium Leaf Miner

Allium leaf miner (ALM) feeding/egglaying scars were detected in chives near Princeton (Mercer Co.), NJ on Tuesday of this week.  This indicates that the first (spring) flight of these flies has now begun and damage will increase.  Additionally, extension personnel at Penn State have reported finding the first feeding scars in several southeastern PA sites within the past few days.  It is believed that all of these occurrences are very recent.

Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion

Growers should consider initiating the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.

Floating row covers, kept on until this flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior),  neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should respond to the first adult generation.  We will attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.

Allium Leaf Miner

Allium leaf miner (ALM) feeding/egglaying scars were detected in chives and scallions near Princeton (Mercer Co.), NJ on Friday of this week.  This indicates that the second (fall) flight of these flies is now underway, and damage is occurring.

Photo: Sabrina Tirpak. Allium leafminer oviposition scars on onion

Growers should consider initiating the control method of their choice at this time.  Affected crops include chives, scallions, garlic, onions and leeks.

Floating row covers, kept on until the second flight ends will help minimize access to plants.  Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain.  Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), and pyrethrin materials (Pyganic (OMRI approved)), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control.

Adult activity and observations of feeding will be reported on in the IPM Update as they occur.  At this time, all growers should respond to the second adult generation.  We will attempt to identify the end of the second flight so that growers know when the risk of infestation has abated.