The Rutgers Farm Health and Safety Working Group is conducting a survey to evaluate the priority needs of New Jersey farmers for training and resource development related to safety and health. As a New Jersey farmer, you are invited to complete this survey by Friday, May 1, 2026. Click here to access the survey and learn more. [Read more…]
Tree Fruit Edition
Seasonal updates on insects, diseases, weeds, maturity dates and cultural practices impacting only tree fruit.
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Fire blight infection predicted week of April 13
NEWA is predicting a high risk for fire blight infection this week as a result of favorable conditions for apple orchards in bloom. Favorable conditions include 1) a certain number of heat units accumulated during bloom for a threshold level of inoculum to be reached; 2) a wetting event to wash the bacteria into infection sites; and 3) the average temperature is above 60°F. If at least two conditions are met during bloom, then the risk for infection is ‘High’ and antibiotics should be applied. A wetting event is not necessary to elevate the risk. Additionally, forecasted wetting events should be carefully considered and a bactericide applied just before or after a rain event.
When using the fire blight model on NEWA, it is important to enter your own “First Blossom Open Date” for your orchard as this can drastically change predictions. You can also enter your orchard’s history with fireblight in the first drop down menu. Lastly, you can enter the date you last applied an antibiotic this season and the model will reset to provide the most accurate predictions. When using the model, it is important to look at the column farthest to the right in the chart titled “Infection Potential EIP Value” since this is the most accurate prediction for our region. Any time the model shows an orange (High) or red (Extreme) output and the value for that date is above 100, an antibiotic application is warranted.
To manage fire blight in both apples and pears, consider using Kasumin at bloom. Kasumin is an antibiotic like Streptomycin and Oxytetratracycline. It contains Kasugamycin which is a different chemistry. Kasumin is only labeled for bloom and petal fall applications while strep and oxytet are labeled for post bloom use (note that Fireline 45 only allows for 1 postbloom application on apple). Using 3 different chemistries in rotation allows for resistance management while extending the protection into the post bloom period when late blossoms typically appear which ever material you use, the addition of Actigard or other plant defense elicitors may improve control. Applications of Apogee or Kudos during bloom can work to prevent shoot blight after petal fall. The use of Actigard and Apogee are especially recommended in new plantings where instances of shoot blight can kill young trees. For further recommendations on these products, Michigan State University published a guide including information on application timing and product rates.
Additionally, for peaches at petal fall, copper formulations should be used to suppress bacterial spot. Generally we recommend starting at 0.5 oz of metallic copper and gradually lowering the rate as the season progresses. The rate applied will depend on the formulation. Dr. Norm Lalancette published a chart listing common copper formulations and rates for peach and nectarine applications. Avoid combining copper with captan especially if it has been overcast for several days. Also avoid acidic spray solutions when applying copper. Dr. Lalancette has published a handy guide for copper applications in early covers. Antibiotics such as Mycoshield or Fireline may also be used and may offer slightly more residual activity during long wetting periods.
Fruit IPM Updates Week of 4/06/2026
Tree Fruit Phenology Update
While tree fruit phenology seemed to advance rapidly late last month into early April across New Jersey, temperatures dropped below freezing overnight early in the week, slowing development and prompting frost warnings, negatively impacting advanced crops and cultivars in bloom. Warmer temperatures are forecast for the weekend and into next week, resuming and accelerating rapid development. It is also important to note that NJ remains under a NJ Department of Environmental Protection Drought Warning, and the entire state is currently in a moderate drought or abnormal dryness according to the US Drought Monitor.
In apples, most varieties have reached pink bud across the state, with early varieties such as Pink Lady now entering bloom in southern counties. In pears, most varieties are at bloom statewide, with Asian pears remaining slightly more advanced. Peach and nectarine varieties have reached full bloom in southern counties and pink in most northern counties, with some early varieties in southern counties beginning to enter petal fall.
April 10, 2026 Hemant Gohil
Assessing the Severity of Frost Damage to Peach and Apple Flower Buds
Figure 1. The brown and shrunken pistil (L) indicates the flower is dead; a green and upright pistil indicates that the flower is alive. Photo by H. Gohil.
The below-freezing temperatures on Wednesday (4/8/26) and Thursday (4/9/26) early mornings are likely to cause frost damage in several peach and a few apple orchards in New Jersey. It got down to 25°F–28°F in Southern NJ, and 22°F -27°F in Central and Northern NJ, and those temperatures could have killed vulnerable blossoms. The night of April 8th saw wind speeds above 10 mph, which mixed the cold air at the bottom with the warm air above. This prevented cold-air stratification and reduced the heat loss from the soil surface and plant tissues. The night of April 9th was even colder, and the wind dropped below 5 mph, almost coming to a standstill for a few hours. This causes the rapid loss of thermal energy from the soil and plant tissues. Most unprotected peach and a few apple orchards were affected by these conditions on the night of April 9th. In several parts of New Jersey, peach flower buds were at full bloom, the most susceptible stage to frost (Fig. 1). In Apples, though most orchards were in the tight cluster or earlier stages of bud development, and few varieties were in the first pink. The critical temperatures for 90% bud kill at these stages are 21°F for the tight cluster and 24°F for the first pink; hence, only a few apple orchards in South NJ were vulnerable to significant frost damage (Fig. 2).
Figure 2. Frost damage to Apple bloom at first pink
In Peach, not all flowers bloom at the same time, which makes frost-damage assessment a little more difficult. Often, many flowers look damaged, but they still bear fruit. This estimate can be even more difficult in some varieties, simply because they bloom so much that even 90% damage can yield close to the full crop. The natural tendency is to look for open flowers, which can easily lead to overestimating the damage. The developing flower buds will quickly die once damaged by a freeze. You can’t tell what will happen just by looking at the flower. The browning of flower petals doesn’t mean the ovary is dead.
You can do a quick, destructive assessment of loss by randomly opening 10-20 flowers per tree; do this on 5-10 trees across an acre or block for each variety. This can give a relative estimate of bloom loss. If you take a more systemic approach, you may get more accurate results. Due to cold-air stratification, cold air settles to the bottom, so more buds are damaged at the bottom; therefore, you want to sample from both the upper and lower branches. Sometimes, the loss of flower buds could be as good as natural thinning. So, flower bud loss may not result in a crop loss.
After opening the flower, if the pistil is shrunken and brown, consider it dead; and if completely green, consider it alive (Fig 1). The pistil is sticking out, and you see it is brown; it could have been pollinated and is in the senescence stage. It is not brown because of frost, but it’s brown because of the normal progression of development. In another scenario, the pistil is brown because it has frost damage, but it still may have done its job of pollination. It served its purpose and senescence because both frost and pollination are over. After pollination and fertilization, rapid hormonal changes enhance fruit development and make them slightly more cold-hardy. So even the destructive analysis is a close approximation.
Figure 3. Uneven development of peach due to frost injuries, represented by very small ripe fruits in PF Flamin Fury 24 (Left) and Silverglo (right), and a significant number of green unripe fruits in Lady Nancy (middle). Photo by H. Gohil.
If frost occurs at the shuck-split or shuck-off stage, the seed/pit will be damaged. But the fruit looks normal. However, they will not reach full size because the nonviable seed cannot produce the hormones required for fruit growth (Fig. 3). Even if they do grow, they may still face other problems. For example, the pit may have sustained damage, predisposing it to shatter during phase III of fruit growth. If you wait for a week to 10 days, it will be easier and more accurate non-destructive assessment. The live flowers will develop normally, and the dead flowers will be shrunken brown mummies that can be flicked away easily. You will still have plenty of time to adjust fruit thinning to achieve a near-normal crop. You should not be in a hurry to do fruit thinning this year! If you see some fruits that have stopped getting bigger and are distinctly smaller, will you want to thin? Maybe after the June drop.
April 8, 2026 Megan Muehlbauer and Pete Nitzsche
North Jersey Tree Fruit and Vegetable Twilight Meeting
North Jersey Tree Fruit and Vegetable Twilight Meeting
Supported by
New Jersey Vegetable Growers Association
April 30, 202
4:30 PM-7:30 PM
Ort Farms
25 Bartley Rd.
Long Valley, NJ 07853
4:15 PM – Registration and Tour of Farmers Market
4:30 PM – Wagon Tour of the Farm
5:00 PM – Light Dinner (Sponsored by NJ Vegetable Growers Association)
5:30 PM – Proper Pesticide Handling, Personal Protective Equipment and Record Keeping
Janine Spies PhD, State Fruit IPM Program Leader, Rutgers NJAES
6:00 PM – Tree Fruit Insect and Disease Update
Kaitlin Quinn, North Jersey Tree Fruit IPM Program Associate, Rutgers NJAES
6:30 PM – Key Management Decisions to Minimize Disease, and Pest Pressure while Enhancing Yield in Strawberry Production
Peter Nitzsche, Agriculture and Natural Resources Agent I, Rutgers NJAES
7:00 PM – Managing Thrips in Vegetable Crops
Amanda Quadrel, North Jersey Vegetable IPM Senior Program Coordinator, Rutgers NJAES
The following pesticide recertification credits will be awarded
1 Unit CORE 3 Units 1A 3 Units 10 3 Units PP2
Please RSVP for the meeting by April 27 with a call to:
Kim Crommelin at 908.788.1338 or kfrey@co.hunterdon.nj.us
Frost Protection for Orchards and Perennial Fruit Crops
The forecast for New Jersey statewide is expected to drop below freezing Tuesday and Wednesday overnight into early morning this week. Fruit crops are most vulnerable in the full bloom to petal fall stages.
Figure 1. Peach bud development stages and corresponding critical temperatures. Adapted from MSU Fruit Extension. Photos by H. Gohil.
Temperatures beginning at 28°F can kill 10% of the flowers when in full bloom and 90% of the flowers when temperatures drop to 24°F or below for more than 30 minutes (Figure 1). Please refer to your local forecast at nearby weather stations to receive the most accurate temperatures during this time period at www.njweather.org/ or https://newa.cornell.edu/.
Management Options for Frost Protection
- Cloth coverings – This can be an effective tool to protect a small number of trees. Sheets, burlap, or frost blankets can provide some protection. Avoid plastic tarps which do not provide efficient insulation and can increase freeze damage on plant tissue. Ensure the covering reaches the ground.
- Irrigation – Irrigate the soil under the trees the day before so any heat will be absorbed. Overhead irrigation is an option if available. The irrigation must stay on until ice starts to melt.
- Heaters – Heat can be sourced through burning propane, natural gas, or oil burning Smudge pots. This could be a valuable investment for a commercial orchard that experiences frost events at critical bloom times; however, it is expensive and highly inefficient as heat produced dissipates quickly.
- Wind machines & helicopters – These devices can be used in conjunction with heat or alone to mix warm air from higher elevation with cold air in the orchard.
- Frost Rescue Sprays – Plant growth regulators such as Promalin can be applied to apples and pears following a frost event to help increase fruit set. The application must be made within 24 hours of the frost event and the trees must be thawed. Follow the label for use restrictions.
References
Gohil, H., Muehlabuer, M., Polanin, N, and Crassweller, R. (2020). Active Frost Protection Methods for Your Orchard. Rutgers Cooperative Extension Bulletin E363. https://njaes.rutgers.edu/e363/
Gohil, H., Muehlbauer, M., Besancon, T., and Ward, D. (2025). Preparing Orchards Against the Frost – Low Tech Strategies. Plant & Pest Advisory Rutgers Cooperative Extension Preparing Orchards Against the Frost – Low Tech Strategies — Plant & Pest Advisory
Demchak, K. (2020). Frost and Freeze Damage on Berry Crops. PennState Extension https://extension.psu.edu/frost-and-freeze-damage-on-berry-crops
