Rutgers University | New Jersey Agricultural Experiment Station | Pesticide User Responsibility

Fruit Crops Edition

Seasonal updates on diseases, insects, weeds impacting tree fruit and small fruit (blueberry, cranberry, and wine grape). Fruit Pest Alerts are also available via this category feed.
 
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April 5, 2025

High Risk of Frost Damage in Peach Orchards

The below-freezing temperatures on Tuesday (4/8) and Wednesday (8/9) will likely invite frost damage to peach orchards in New Jersey. In several parts of New Jersey, peach flower buds are in the bud swell to the petal fall stage.

Figure 1. Peach bud development stages and corresponding critical temperatures. Adapted from MSU Fruit Extension. Photos by H. Gohil

Bloom progression in southern New Jersey indicates that except for very few delayed blooming varieties such as ‘Gloria’ and “Scarlet Rose’ most varieties will be in the bloom or post-bloom, next week. These are the most vulnerable stages to frost damage (Figure 1). Often, the cause is a few hours below the injury threshold temperature for the developing buds. Monitoring the growth stage and weather conditions will help in determining the actual threat of frost damage and whether to start a frost protection system.

Monitor the orchard temperature. Frost can occur when the ambient temperature dips below freezing (32°F). The hourly falling rate and the lowest forecasted temperature should also be monitored.  Because the threshold temperature for each bud development stage is different, and a slight temperature difference can make a difference between frost damage and no damage, it is essential to know the precise temperature. In most cases, the orchard temperature will not be the same as forecasted or reported by the weather channels because the weather station could be farther away than the orchard location. Remember that the nighttime temperatures often dip below the predicted temperatures. It is crucial to have a thermometer in the orchard. Even the data from the nearby weather station could be unreliable. Also, frost alarm systems can give precise temperatures in the orchard and send warning messages to your mobile phone at a set temperature. Some systems can also report wet-bulb temperature, essential when using overhead irrigation for frost protection (Figure 2).

Monitor the bud development stage for each variety block, starting from bud swell. Critical temperatures have been researched and calculated for each bud development stage. For example, at 25°F, a peach orchard in full bloom can expect up to 90% crop loss, but at the first pink stage, it will suffer only marginal loss (Figure 1).

The critical temperature for damage at a particular bud stage may vary by 4-5°F depending on temperatures during the previous few days before the cold event.

Figure 2. Weather Station with in-built frost alarm system in Peach Orchard, Medford, Southern NJ.

Therefore, growers should use caution when using these published critical temperatures for active frost protection methods. Also, knowing the bud development stage for all varieties in the orchard will allow you to prioritize varieties or blocks that need frost protection.

Cloud coverage:  Clear skies enhance radiative heat loss into the sky, which results in lower temperatures than when there is cloud cover, which can trap radiant energy from the ground.

Wind Speed: Wind increases the rate of heat loss from the ground and plant tissues. Low speed allows the formation of the inversion layer. Most frost protection methods will have reduced efficiency at wind speeds above 10 mph. Fire or heat application-based methods are less effective at wind speeds below five mph.

The frost protection method should only be employed after determining the actual risk of frost and considering the cost-benefit analysis. The articles below have information on passive and active frost protection methods.

Filed Under: Blueberry, Cranberry, Fruit, Strawberry, Tree Fruit, vegetable, Wine Grape Tagged With: , , , ,
April 4, 2025

NJ DEP issues Open Burn Permit from April 6 through April 12, 2025

To Agriculture and Agribusiness Representatives:

The New Jersey Department of Environmental Protection (DEP) is issuing this notice concerning open burning due to colder spring overnight temperatures presently forecasted for areas of New Jersey from April 6 (Sun), through April 12 (Sat), 2025, which could adversely affect fruit, vegetable, and floriculture crops in bloom or near bloom around the state. The DEP intends to exercise its authority and discretion under the Air Pollution Control Code, N.J.A.C. 7:27, et seq., and other applicable authorities to permit the following procedure for open burning or the use of smudge pots to assist farmers in protecting their crops in low temperatures. These cold events could adversely affect some of the fruit, vegetable, and floriculture crops. 

Note: The NJDEP and New Jersey Forest Fire Service caution all farmers and agriculture businesses with respect to the use of open burning in high wind velocity conditions. Please take note that farmers are encouraged to utilize smudge pots is warming as necessary during higher wind conditions. Use of open burning when wind velocity is greater than 5mph is strictly prohibited, may contribute to wildfire risk, and can carry significant penalties.

For the Burn Permit Application form, please see: https://www.state.nj.us/dep/parksandforests/fire/docs/ag-permit.pdf

The DEP intends to exercise its authority and discretion under the Air Pollution Control Code, N.J.A.C. 7:27, et seq., and other applicable authorities to permit the following procedure for open burning or the use of smudge pots to assist farmers in protecting their crops in low temperatures. Procedures for Open Burning and the Use of Smudge Pots Pertaining to New Jersey Fruit, Vegetables, and Floriculture

  • Facilities that believe they will conduct open burning or use smudge pots must provide notice to the DEP 24-hour Communications Center at 1-877- WARN DEP (1-877-927-6337) prior to the use of either technique. • Facilities should notify DEP if they believe they may need to use either technique. • Where DEP cannot be notified in advance, a facility must notify DEP the following morning no later than 9:00 a.m. • The following information must be provided to DEP upon each notification:
  1. Name of the individual deciding to conduct the open burning or use of smudge pots.
  2. Name of the farm or facility
  3. Actual street address of the facility on which either technique will be used.
  4. Contact person and telephone number at the facility.
  5. Predicted temperature (in F) at facility anticipated when the technique will be used.
  6. Predicted wind speed at facility anticipated when the technique will be used.
  7. Predicted hours of open burning or use of smudge pots
  8. Predicted material to be used for open burning or use of smudge pots.
  • Upon completion of the open burning or the use of smudge pots, the facility must provide the following information within 2 business days to the DEP 24-hour Communication Center at 1877-WARN DEP (1-877-927-6337):
  1. The DEP Communications Center incident number
  2. Ambient orchard(s) temperature (in F) at the time the technique was used.
  3. Actual wind speed at the orchard(s) location at the time the technique was used.
  4. A statement that all restrictions in the open burning or use of smudge pots were followed. The restrictions are noted below.

RESTRICTIONS

  • NO OPEN BURNING WILL BE PERMITTED UNLESS: 1. The temperature within the orchard area is at or below the critical temperature for the bud stage. The attached report lists the critical temperatures for New Jersey crops. -AND 2. The wind velocity is less than 5 miles per hour.
  • Authorized open burning material may consist only of either the following materials: clean scrap lumber (untreated), felled trees, prunings, hedgerows or firewood.
  • ABSOLUTELY NO refuse, trade waste, tires, garbage, or other solid waste may be added to the authorized open burning material. Introduction of any unauthorized material into an authorized open burn is a violation of environmental laws and may carry significant penalties.
  • Smudge pots are only permitted when the temperature within the orchard area is at or below the critical temperature for the bud stage (wind velocity restriction does not apply).
  • Smudge pots must be fueled only with either kerosene or No. 2 fuel oil.
  • Failure to abide by these provisions and restrictions may result in enforcement action.

 

 

Filed Under: Blueberry, Cranberry, Fruit, Landscape, Nursery, & Turf, Nursery, Strawberry, Tree Fruit, vegetable, Wine Grape Tagged With: , , , ,
April 3, 2025 and

Tree Fruit IPM Report April 3, 2025

Tree Fruit Phenology:  

Tree fruit phenology is advancing in southern counties based on historical observations. In southern counties some early blooming varieties are about 50 % bloom. Redhaven was pink on March 30, about 6 days earlier than the median observation date. Red Delicious was at ¼” green tip on March 24, about 8 days earlier than the median observation date. Most apples are at tight cluster, and pears are about white bud to early bloom. Plums are full bloom.  

Peach: 

Brown Rot: Blossom infections from the brown rot fungus can occur whenever pistils are exposed and a favorable climate exists. Infections can occur during any wetting period when temperatures are between 41 and 86 °F. However, optimum conditions for infection occur with wetting and temperatures in the mid 70’s. During long wetting periods (several days or more) blossoms can be infected regardless of temperature. Generally, infections that occur when conditions are sub optimal are less severe. Blossoms and fruitlets will remain susceptible until the pistil dessicates (sometime between petal fall and shuck split). Initiate coverage for blossom blight starting at pink for short petaled varieties and 5-10% bloom for showy flowers. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates. 

 

Fig. 1 Tip die back likely caused by bacterial spot (photo D. Schmitt).

 

Bloom Cankers: Bacterial Spot is a key pest of Peach, Nectarine and Plum and in some years can cause significant losses. It is caused by the bacterium Xanthomonas arbicola pv. pruni. Black tip cankers caused by bacterial spot usually appear during or just after bloom. Typical symptoms are a gradual blackening of the tip with dead tissue moving down the twig and is often observed on highly susceptible cultivars (Fig. 1). Tip die back may also occur from abiotic factors such as frost. Tip die back from frost is often accompanied by blind wood usually 6-8 inches below the tip where leaves and flowers have fallen off after being killed by a freeze. Spring cankers that are caused by bacterial spot may also form around flower buds and may be confused with constriction canker or brown rot (see below) Spring cankers are not commonly observed in our region. 

 

 

Fig. 2a Dead bud from constriction canker

In some cases the twig may appear healthy and a shoot begins growing from the tip only to die back after leafing out and flowering. This is often a symptom of fall infections of leaf scars by constriction canker. Many times a bud that was infected in the fall and never leafed out may be found just below the new shoot that is dying (Fig. 2a). Mild gummosis around the dead bud may also be observed. These symptoms may be more prevalent in old trees that have a history of the disease. Growing tips may also be killed if the leaf scar was infected and may be confused with black tip from bacterial spot. 

Another disease that causes cankers on flower buds is Monolinia fructicola, the cause of brown rot blossom blight. During bloom flowers that are infected by the brown rot fungus will rapidly dessicate and form a canker around the bud similar to late winter or ea

Fig 2b. Dead bud and canker from fall infection by constriction canker. (photo D. Schmitt)

rly spring infections by constriction canker (Fig 2b.). These can be distinguished from blossom blight by waiting a few days to see if the brown rot sporulation appears on the canker. Symptoms of brown rot also differ from constriction canker in that excessive gummosis will appear at the canker site (Fig. 3).

Fig. 3 Blossom blight canker. Note sporulation and excessive gumming around detached flower. (Photo D. Schmitt)

 

 

 

 

 

 

 

 

Oriental Fruit Moth: A biofix point for OFM was set on 4/2 in southern counties. OFM biofix is defined as the first sustained trap captures (2 or more consecutive days of trap captures of more than one adult.) It usually coincides with full bloom (about 4/13 in southern counties) but can start as early as late March. The first insecticides for first generation Oriental Fruit Moth control should be applied at 170-200 degree days (base 45 deg F) after biofix. This timing generally coincides with petal fall in peaches. Timings can be calculated using the degree day calculator at the NEWA website by choosing the weather station nearest your farm, entering the biofix date as the start date, and choosing base 45 in the “degree day type” menu. Mating disruption may be substituted for insecticide applications by placing dispensers or initiating sprayable formulations of pheromone in the orchard anytime before biofix. See the NJ Commercial Tree Fruit Production Guide for more information. 

 Green Peach Aphid: GPA colonies begin forming sometime during bloom. Examine trees for the presence of colonies from pink to shuck split. Count the number of colonies on ten trees and use a treatment threshold of 2 colonies/tree at petal fall for peach, and 1 colony/tree for nectarine. The best way to scout for aphids during bloom is with a beating tray. Blossoms may also be collected, opened, and examined for the presence of aphids using a hand lens. See the NJ Commercial Tree Fruit Production Guide for recommended materials and rates. 

Tarnished Plant Bugs and Other Catfacing Insects:  Catfacing insects cause little damage at this time of the year. Catfacing insects will become more of an issue as temperatures warm and mowing and other ground cover activities become more common after bloom. Insecticide applications are not recommended until after all petals are off. 

 Scale Insects: Oil applications may be safely applied up to pink on peach. Other options include Centaur, Sivanto Prime, Esteem, and Venerate. These products can be combined with oil or applied alone. See the apple section below for more information. 

Apple: 

Diseases: Fire Blight, Apple Scab, Rust diseases, and Powdery Mildew are the main targets at this stage. The NEWA apple scab model is estimating about 11% ascospore maturity as of 4/22 in southern NJ with 6% of cumulative ascospores discharged. The model estimates about 10% ascopsore maturity for Northern Counties with 8% ascospores released. Primary apple scab spores are released during any substantial infection period. Between tight cluster and first cover include products effective for powdery mildew and cedar apple rust. 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 is only labeled for 1 post bloom 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, Lifegard, or other plant defense elicitors may improve control. 

 Rust Diseases: The two most common rust diseases that affect pome fruit are Quince Rust and Cedar Apple Rust. In some years these diseases can be troublesome in commercial orchards. Most disease control programs for scab will also control rust. In organically managed blocks in the east options are limited for approved materials that are effective for rust. Potassium Bicarbonate products have shown good efficacy for rust diseases in trials performed in Virginia. Organic growers should seek out and plant rust resistant cultivars. Cultural controls are not practicable due to the widespread presence of alternate host Junipers both wild and cultivated. Rust disease development on junipers should now be producing large spore releases during wetting periods. See this link for pictures of rust on pome fruit and juniper. 

Scale and Rosy Apple Aphid: One sees many recommendations for mixing materials efficacious for scale such as the insect growth regulators (Centaur; Esteem) with delayed dormant oil applications. The general consensus from data review seems to be that the addition of scale insecticides to oil do not significantly improve control over oil applied alone. Recent tests performed by Dr. Neilsen’s lab indicate that Sivanto Prime, Centaur and Venerate when applied alone in the pre-bloom period are comparable to dormant oil for scale control. Esteem has good efficacy for scale when applied up to to 1/2″ green. Closer has some efficacy against scale, however it has not been evaluated for control of overwintering scale. Esteem, Closer, Sivanto Prime, and a new product: Versys, applied either alone or with oil at 1/4″ to 1/2″ green all have good to excellent ratings for rosy apple aphids. See the NJ Commercial Tree Fruit Production Guide for more information. Note that the Virginia Spray Bulletin for Commercial Tree Fruit Growers lists syllit as incompatible with centaur. 

 European Red Mite; San Jose Scale: Oil applications for mite suppression and scale control should start at 1/4” green. Apply 2% dilute or 4-6 gals oil/acre concentrate at 1/4”green to tight cluster; 1% dilute or 2-3 gals/acre concentrate at tight cluster to pink. Oil should not be applied if temperatures are expected to dip into the mid 30’s within 48 hours of application, and captan or sulfur should not be applied within 14 days of any applications of oil or oil based formulations. Check the product labels for additional phytoxicity precautions. 

 Pear: 

Pear Psylla:  Dormant oil applications should have already been started to deter psylla egg laying. At the green cluster stage a pyrethroid is generally included with oil to knock down adults migrating into the orchard.  In lieu of oil, Surround may also be applied starting at swollen bud and continued through bloom. If using Esteem for psylla control make one application delayed dormant through popcorn or two applications; one at delayed dormant through popcorn and one at petal fall. Centaur is also effective and one application may be made pre-bloom or at petal fall. Sivanto Prime is also labeled for early season applications and should be combined with oil. 

Pear Diseases: Copper for fire blight suppression should not be applied past the green tip stage if fruit russet is a concern. Include effective materials such as Ziram or EBDC formulations for Pear Scab and beginning at the cluster bud stage. At white bud use products effective for rust, pear scab, and fabrea leaf spot. Particular attention should be paid to rust on asian varieties. Start planning for blossom sprays using antibiotics. For 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. Using 3 different chemistries in rotation allows for resistance management while extending the protection into the post bloom period when late blossoms typically appear. Whichever material you use, the addition of Actigard, Lifeguard or other plant defense elicitors during bloom may improve control. 

  

Filed Under: Tree Fruit, Uncategorized
March 30, 2025

Last Call: Farmer Resource Fair in Somerset County

All New Jersey farmers are invited to attend this Farmer Resource Fair which will feature an array of agricultural service providers. In-between a light breakfast and a hearty lunch, there will be engaging presentations and opportunities to visit with service providers at their table displays. The program schedule, as well as a preliminary list of service providers who’ve confirmed their attendance, is included below.

The event will be held on Friday, April 11, 2025 from 8:30 am to 2:00 pm at the Ted Blum 4-H Center located at 310 Milltown Road, Bridgewater, NJ 08807.

Click here to register for this free event (registration is required). Please register by April 1, 2025.

This collaborative event is being organized by Rutgers Cooperative Extension of Somerset County, Somerset County Agriculture Development Board, and the State Agriculture Development Committee Next Gen Program. We hope you will join us! [Read more…]

Filed Under: Christmas Trees, Commercial Ag Updates, Field, Forage & Livestock, Fruit, Landscape, Nursery, & Turf, Vegetable Crops
March 28, 2025

Last Call: Stop the Bleed Training in Burlington County

Person applying a tourniquet to a mannequin Rutgers Cooperative Extension, in partnership with the Vegetable Growers Association of NJ and the Rutgers NJ Medical School, will host a Stop the Bleed training on Tuesday, April 8, 2025 from 10:00 am to 12:00 pm at the Rutgers EcoComplex located at 1200 Florence Columbus Rd, Fieldsboro, NJ 08505.

Don’t miss this opportunity to learn the life-saving skills of pressure application, wound packing, and use of tourniquets. Attendees of this free training will also receive a complementary bleeding control kit. Space is limited, register today! Please complete our pre-registration form by Monday, April 1.

Questions? Email Kate Brown, RCE-Somerset County Ag Agent, at kbrown@njaes.rutgers.edu or call 908-526-6293.

Filed Under: Commercial Ag Updates, Field, Forage & Livestock, Fruit, Landscape, Nursery, & Turf, Vegetable Crops Tagged With:
March 26, 2025 , , and

Preparing Orchards Against the Frost – Low Tech Strategies

Frost is common in the northeastern US. However, frost events during bloom, specifically in orchard crops, can be economically devastating. Often, the cause is a few hours below the injury threshold temperature for the developing buds, as cooler nights result in the rapid loss of thermal energy. Several passive or low-tech strategies can help maintain a slightly higher orchard floor temperature and potentially prevent substantial crop loss.

Site selection is the most effective frost protection method. When planning a new orchard, selecting a site with proper cold air drainage is the most valuable decision a grower can make and enjoy the rewards for many years. Cold air drainage is essential, so avoid buying a site or planting trees on the site that accumulate cold air. Also, identify areas where the cold air moves in and out. When possible, plant early blooming varieties in the least frost-prone areas and plant delayed and or extended bloom varieties in frost-prone areas.

Table 1. Relative temperature differences are influenced by orchard floor conditions (Courtesy, Robert Crassweller, PSU).

Do not invite the frost with excess vegetation and ground cover. The management of weeds along the row and sod between the rows will influence orchard temperatures. The bare ground will absorb more heat during the day and release more heat at night than soil covered in vegetation (Table 1). During the day, 45-50% of solar radiation gets reflected or absorbed by the atmosphere, and the earth absorbs the remaining 50-55%. Vegetation reduces this heat transfer to the soil because it reflects light before it can reach the soil surface. Removing tall weeds and windbreaks along the edges of orchards will also help improve airflow and limit the accumulation of cold air pockets in some areas of the orchard. This can be particularly important during spring bloom when just a few more degrees can make the difference between killing the flowers or not!

Extremely low grass cutting: Maintaining sod between the rows at a minimum height by frequently mowing will help with frost protection. Similarly, keeping the rows weed-free by using postemergence herbicides to kill emerged weeds and removing weed residues from the previous season will maximize the warming of the soil by solar energy during the day. Maintaining weed-free rows should also be considered by applying residual herbicides in the fall. Depending on herbicides applied in the fall, this will prevent or reduce weed emergence in early spring and give you more flexibility for applying your residual and postemergence herbicides in spring. 

The cold air drain machine has a fan that pulls cold air from the surrounding ground and pushes it into the sky. This is effective in a lower section of the orchard or the end of the vineyard where the cold air drains due to a slight slope. Placing the machine in the middle of the orchard may prove ineffective as the pulled cold air could settle back into the orchard unless there is a low inversion layer to mix with warmer air. Using the cold air drain machine can enhance the effectiveness of low grass cutting. The machine costs around $15,000, and its operating cost is much less than other active frost protection methods.

Wet soil slows the release of thermal energy on frost night. However, the soil profile must be thoroughly wet. This can be achieved by irrigating the soil to field capacity (maximum water holding capacity of that soil). Also, the temperature must be warmer during the preceding days to pack sufficient heat into the soil. Sandy soils store less energy than loamy soils because there is more air space between soil particles than loamy soils. Heavier soils may require more than 8–10 hours of irrigation to reach field capacity.

Delayed pruning delays bud development, which helps avoid damage from early spring frosts. Years of observation in commercial orchards in the northeast indicate that more buds survive after a frost event, specifically in peaches, if the pruning is delayed. Often, large farm operations begin pruning early in the dormant season due to labor availability and time constraints. In such cases, avoid pruning upper branches until the risk of a late freeze has passed. Also, avoid hard blossom thinning on peaches on lower branches or blossom thinning altogether. Instead, focus only on fruit thinning, which can serve as insurance against crop loss. Remember that any available crop will likely command a good price in frost years.

Combining the above methods can have a cumulative effect on overall frost protection in the orchard. Keeping trees healthy with proper nutrient and pest management is also important. Healthy trees may still lose a crop but are more likely to survive the next season than poor vigor and diseased trees. The success of Frost Protection will also depend on understanding each method’s working principles and the combination of environmental factors necessitating its use. The bulletin https://njaes.rutgers.edu/e363/ explains what to monitor before a frost event and active frost protection methods such as irrigation, heat application, and air mixing.

Filed Under: Blueberry, Cranberry, Fruit, Nursery, Strawberry, Tree Fruit, vegetable, Wine Grape Tagged With: , , , ,