What is the Right Time to Terminate Irrigation in Soybean?

Knowing the ideal time for terminating soybean irrigation is very important. Stopping irrigation too soon decreases kernel size and grain yield while stopping it too late incurs unnecessary extra cost. Using information on “crop development stage” and “soil moisture levels in root zone” is helpful in determining ideal termination time for irrigation.

The right pods to check

First step is to check with your seed dealer to see what variety (indeterminate or determinate) of soybean you are growing. For indeterminate variety, the pods at the top four nodes of the main stem, having fully developed leaves, should be examined to determine the growth stage. In case of determinate varieties, growth stage identification can be performed anywhere throughout the plant as pods develop uniformly along the stem. For growth stage assessment, include plants from all representative field sections (possibly known), with particular attention to later-developing areas.

Identify the growth stages

  • R5 is a “beginning seed” stage when seed starts to develop, attaining 1/8 inch of length.
  • R6 is a “full seed” stage when pods have full seed (green) that completely fills the pod cavity.
  • R6.5 is a “late seed fill” stage when seed (contained in the pod) gets fully separated from the protective membrane of the pod wall.
  • To look for photos of different soybean growth stages (including R5, R6, and R6.5), please visit this link- https://extension.msstate.edu/publications/guide-soybean-growth-stages

How to make a final decision on irrigation

  • Once your soybean plants are at R6.5, it’s generally the right time to terminate irrigation if your field’s root zone has sufficient moisture to sustain the rest of seed filling. If your soybean plants are at R6, they still need irrigation.
  • To guide irrigation termination timing, it is helpful to i) Keep in mind that the sandy soils in Southern New Jersey have limited soil-water reserves, ii) Check moisture in root-zone with sensors or soil sampling at or just before soybean reaches R6.5 stage, iii) Stay up to date with the weather forecasts, and iv) Reassess the decision in case expected rainfall does not come.

Summary/ Takeaway Message

Use R6.5 growth stage identification method and soil moisture information to decide your irrigation termination time. Do not rely only on the calendar, leaf color, or mature-looking pods on lower part of the plant.

References

Questions? Contact Ramandeep Kumar Sharma at rs2794@njaes.rutgers.edu.

Fruit IPM Report 8/25/2026

As we approach the end of August, harvest of blueberries and peaches are ending while apple and grape harvest is beginning across the state. Temperatures for the month, particularly in the last week have been mild with high relative humidity. Heavy periods of rainfall were seen late last week with some areas recording more than 2 inches. Below are recent observations and considerations for pest management in fruit crops statewide.

Apples
Disease Management Considerations

Summer disease control is coming to an end for early-season apple varieties. Mid- to late-season varieties will need further applications on a two-week schedule, or every 2 inches of rain, using single-site materials from FRAC groups 11, 7, or 3 to manage summer rots, sooty blotch, and fly speck. See the NJ Tree Fruit Production guide for effective materials. 

Fire blight strikes that are apparent should be pruned out during dry weather, cutting 8 to 12 inches below diseased wood. Pruning tools are sanitized after each cut by dipping them into a 10 percent bleach solution. Young trees with fire blight cankers that have spread to the main leader should be removed. 

Insect Update

Brown Marmorated Stink Bugs (BMSB) are increasing at some farms and injury to fruit has been observed (Figure 1). If stinkbugs are a concern for your orchard, see the NJ Tree Fruit Production guide for effective materials. 

Injury from stink bug feeding on fruit looks like bruising and corking of flesh just under the skin.

Figure 1. Injury from stink bug feeding on fruit looks like bruising and corking of flesh just under the skin.

Codling Moth (CM) pressure remains low in orchards statewide; however, we are seeing damage to fruit where populations have been high. Additional treatments should be applied if trap captures exceed 5 moths/trap.  

Woolly apple aphids (WAA) are increasing in some orchards and spreading to shoots, particularly in older orchards with dense canopies. Sefina has a 7-day PHI and is a good option to manage WAA.  Assail will also help to suppress WAA.  

Scale crawler emergence is past peak and declining. Options at this point include Group 4A products labeled for scale, including Assail, and the bioinsecticide Venerate. Venerate has a 0-day PHI, making it useful for blocks near or at harvest. 

Dogwood borer (DWB) continues to be captured in pheromone traps in orchards statewide. If this pest has been a problem in your blocks in the past, you may consider adding mating disruption next year. 

Traps

Average Trap Captures in Apple – Southern Counties

  Week   STLM   TABM   CM   OFM   DWB   AMBROSIA BEETLE   BMSB  
5/11/2026   18    11    6   3     25     2   –  
5/18/2026   16   21   3   10     54   13   –  
5/25/2026   1.3   23   2   2     71   7   –  
6/1/2026   378   33   3   2     49   6   0.4  
6/8/2026   258   11   2   1     61   21   1.2  
6/15/2026  355  4  0.6  1.5    57  13  0.8 
6/22/2026  178  5  0.6  2    54  8  1.2 
6/29/2026  504  0.3  0.1  0.5    27  12  0.8 
7/6/2026  202  1.1  1.6  0.6    25  7.5  0.6 
7/13/2026  226  0.9  1  1    33  1  1.6 
7/20/2026  253  1.8  2  3    26  2.3  2.4 
7/27/2026  246  1.5  5  1.6    38  2  1.6 
8/3/2026  253  1.6  2  1    47  1.4  2.6 
8/10/2026    1  1  1    48  2.7  0.8 
8/17/2026  375  1.9  1  1    47  2.6  2.2 

 

Average Trap Captures in Apple – Northern Counties

  Week   STLM   TABM   CM   DWB   AMBROSIA BEETLE   BMSB  
5/11/2026   13.7   1.5   1.8   12.8   1.1   –  
5/18/2026   8.3   13.25   2.4   18.5   10.8   –  
5/25/2026   2.2   13.75   1.2   24.5   5.1   –  
6/1/2026   25.1   24.3   3.4   23.8   9.4   0.3  
6/8/2026    94  22.3  0.3   24.6    18  1.4  
6/15/2026  68  22.3  1  22.6  14  1.1 
6/22/2026  105.9  35  0.7  27.2  8.2  0.5 
6/29/2026  100  11.5  0.3  28.9  5.3  0.3 
7/6/2026  50.2  7.3  0.6  26.4  5.2  0.2 
7/13/2026  52.4  7  0.5  24.8  5.3  0.2 
7/20/2026  69.7  2.5  0.7  27.4  4.3  0.1 
7/27/2026  92.4  2  0.6  30.6  5.3  0.2 
8/3/2026  78.6  1.8  0.5  2.3  2.2  0.5 
8/10/2026  56.5  3.3  0.7  26.3  3.2  0.1 
8/17/2026  23  3.3  0.8  26.9    0.4 

[Read more…]

Salem County Agronomy Twilight Meeting 2 – This Coming Monday!

Please join us Monday, August 31, 2026, from 6:00–8:30 p.m. at Rutgers Cooperative Extension of Salem County in Woodstown for an evening of timely field crop production updates.

Rutgers Cooperative Extension – Salem County
51 Cheney Road, Woodstown, NJ

Program begins at 6:00 p.m.; please arrive early.

Schedule & Topics

6:00 p.m. – Welcome & Introduction – Salvatore Mangiafico and Ramandeep Kumar Sharma, Rutgers Cooperative Extension

6:15 p.m. – Sulfur in Coastal Soils – Jarrod Miller, University of Delaware

6:45 p.m. – Sweet Corn Pest Management Updates: Scouting, IPM Strategies, and Responsible Pesticide Use – Amanda Quadrel, Rutgers Cooperative Extension

7:15 p.m. – Assessment of Agricultural Crop Damage by Black Bear in New Jersey – Salvatore Mangiafico, Rutgers Cooperative Extension

7:45 p.m. – Corn Lodging Insights and Agronomic Research Updates – Ramandeep Sharma, Rutgers Cooperative Extension

8:15 p.m. – Wrap-Up, Evaluations, and Pesticide Credit Submissions

Pesticide Recertification Credits (Credits are pending NJDEP approval)

Credits have been applied for: CORE (1), 1A (2), PP2 (2), and Category 10 (1)

Registration

Phone: 856-769-0090
Email: e_dehart@salemcountynj.gov

Please save the date and join us for an evening of practical information and discussion relevant to New Jersey field crop production.

We look forward to seeing you August 31!

Soybeans at Full Pod (R4) Growth Stage: What Farmers Need to Know Now to Protect Yield Potential

With the New Jersey soybeans reaching the R4 (full pod) growth stage, the crop is entering a crucial period for yield development. The plants shown below are at around R4 growth stage. For farmers in Southern New Jersey, this is a crucial time to scout fields closely and minimize stresses that can affect pod and seed development.

         

(Photo Credit: Ramandeep Kumar Sharma; Aug 24 2026)

How to identify R4 stage in soybeans?

Soybean is reached at the R4 (full pod) growth stage when a plant has a pod at least 3/4 of a inch long at one of the four uppermost nodes on the main stem, with a fully developed leaf at that node. To determine whether the crop has reached R5 (beginning seed), open a pod at one of these upper nodes. R5 begins when the seed inside the pod is at least 1/8 inch long.

Why R4 is so important for soybeans?

R4 marks the starting of one of the most critical periods for soybean yield determination. At R4 stage, pod growth is fast, and seed development is starting. From R4 through early seed filling, stresses such as moisture/nutrient deficiency, disease, insect injury, and excessive defoliation can reduce yield by increasing the abortion of flowers, pods, and developing seeds. The crop has some ability to compensate later through seed growth, but that compensation is limited.

What should soybean farmers do now?

  • Monitor soil moisture: Adequate moisture is particularly important from R4 through early seed development. This deserves close attention in Southern New Jersey’s sandy and coarse-textured soils, which can dry rapidly during hot, dry periods. Where irrigation is available, monitor soil and crop conditions and irrigate when needed.
  • Keep scouting for insects and diseases: Continue checking the canopy for defoliation, pod-feeding insects, and disease symptoms. Make pesticide decisions based on scouting, pest or disease pressure, crop stage, economic considerations where applicable, and the current product label but not simply because the crop has reached R4.
  • Check for nutrient stress: Continue watching for nutrient deficiency, especially in fields with low soil fertility or a history of nutrient loss. Rutgers recommends that soybean fertility management be based on recent soil tests and realistic yield goals. Rutgers also identifies potassium and sulfur as important considerations in New Jersey soybean production and notes that nutrient stress can occur in Southern New Jersey soils because of nutrient leaching.
  • Don’t stop scouting weeds: A closed soybean canopy suppresses many weeds, but late-season escapes can still produce seed and interfere with harvest. Any herbicide application must follow the current product label, including crops, weed, timing, rate, and preharvest restrictions.

Summary

R4 is not the time to stop scouting, it is the time to pay closer attention. Protecting adequate soil moisture, healthy foliage, developing pods, and seed formation during R4–R6 can help protect soybean yield potential. On checking pods, if a seed (at least 1/8 inch long) is found inside a pod at one of the upper four nodes, it means the plant has reached R5 (beginning seed).

References

  • Sharma, R. K., & Heckman, J. 2026. Nutrient and Management Tips for New Jersey Soybean Production. Rutgers Cooperative Extension, Plant & Pest Advisory, June 26, 2026.
  • Heckman, J. R. 2009. Soil Fertility Recommendations for Soybean. Rutgers Cooperative Extension, Fact Sheet E323.
  • Bravo, M. 2021. Soybean insect vectored, internal stem, root disease monitoring now through pod fill. Rutgers Cooperative Extension, Plant & Pest Advisory, July 9, 2021.
  • Bravo, M. 2021. Field crop progress mid-July, Salem County. Rutgers Cooperative Extension, Plant & Pest Advisory, July 17, 2021.

Fruit IPM Report August 17, 2026

 

Apples
Disease Management Considerations

Summer scab, rots, sooty blotch, and flyspeck are the main targets currently, and are present in orchards throughout the state. Captan plus a phosphorous acid like Prophyt or Rampart can provide good summer disease control. Add single-site products such as Topsin, Merivon, Luna Sensation, and Pristine for improved control. Consider the pre-harvest interval as we approach harvest. Time applications before rain events through the growing season according to the cover spray rule of applications every 2” of rain or 14 days, whichever comes first. 

Diseases observed on developing apples a) white rot, b) bitter rot, and c) sooty blotch and fly speck.

Figure 1. Diseases observed on developing apples.

Insect Update

Codling Moth (CM) trap captures have decreased compared with previous weeks, and most are below the treatment threshold. Additional treatments are not recommended unless there are more than 5 moths per trap. 

Scale crawlers are active and can be found feeding on fruit (Figure 2). Second-generation crawler emergence is estimated to be at or just past peak. Control options at this point include Assail, Belay, Actara, and Sivanto. Venerate has a 0-day PHI, making it useful for blocks near or at harvest.

San Jose scale crawlers on maturing apple fruit.

Figure 2. San Jose scale crawlers on maturing apple fruit.

Aphid populations, on average, remain below treatment levels, but are increasing as dry, hot weather continues. A treatment threshold is set at 50% of the terminals infested with live colonies. Minimize the use of pyrethroids to manage insect pests, as they can knock down beneficial organisms and predators. Research from Dr. Monique Rivera at Cornell University has demonstrated good control from Sefina for Woolly Apple Aphid in late summer. 

Brown Marmorated Stink Bugs are active in orchards statewide; however, observations of injury remain low in managed orchards. See the NJ Tree Fruit Production guide for effective materials on harvesting fruit.  

White Apple Leafhopper second-brood activity is active in South Jersey orchards. Check the undersides of 20 leaves per tree across 5 trees per block; the treatment threshold for the second brood is 2 or more leafhoppers per leaf. Feeding at this stage causes leaf mottling, and excrement can degrade fruit quality right before harvest. High adult populations can also create a major nuisance for harvest crews. If treatment is needed, thorough coverage on both upper and lower leaf surfaces is essential for effective control. Sivanto Prime, Leverage 360, and Assail are effective materials.  

Traps

Average Trap Captures in Apple – Southern Counties

  Week   STLM   TABM   CM   OFM   DWB   AMBROSIA BEETLE   BMSB  
5/11/2026   18    11    6   3     25     2   –  
5/18/2026   16   21   3   10     54   13   –  
5/25/2026   1.3   23   2   2     71   7   –  
6/1/2026   378   33   3   2     49   6   0.4  
6/8/2026   258   11   2   1     61   21   1.2  
6/15/2026  355  4  0.6  1.5    57  13  0.8 
6/22/2026  178  5  0.6  2    54  8  1.2 
6/29/2026  504  0.3  0.1  0.5    27  12  0.8 
7/6/2026  202  1.1  1.6  0.6    25  7.5  0.6 
7/13/2026  226  0.9  1  1    33  1  1.6 
7/20/2026  253  1.8  2  3    26  2.3  2.4 
7/27/2026  246  1.5  5  1.6    38  2  1.6 
8/3/2026  253  1.6  2  1    47  1.4  2.6 
8/10/2026   NA 1  1  1    48    0.8 

 

Average Trap Captures in Apple – Northern Counties

  Week   STLM   TABM   CM   DWB   AMBROSIA BEETLE   BMSB  
5/11/2026   13.7   1.5   1.8   12.8   1.1   –  
5/18/2026   8.3   13.25   2.4   18.5   10.8   –  
5/25/2026   2.2   13.75   1.2   24.5   5.1   –  
6/1/2026   25.1   24.3   3.4   23.8   9.4   0.3  
6/8/2026    94  22.3  0.3   24.6    18  1.4  
6/15/2026  68  22.3  1  22.6  14  1.1 
6/22/2026  105.9  35  0.7  27.2  8.2  0.5 
6/29/2026  100  11.5  0.3  28.9  5.3  0.3 
7/6/2026  50.2  7.3  0.6  26.4  5.2  0.2 
7/13/2026  52.4  7  0.5  24.8  5.3  0.2 
7/20/2026  69.7  2.5  0.7  27.4  4.3  0.1 
7/27/2026  92.4  2  0.6  30.6  5.3  0.2 
8/3/2026  78.6  1.8  0.5  2.3  2.2  0.5 
8/10/2026  56.5  3.3  0.7  26.3  3.2  0.1 

Peaches
Disease Management

Brown rot has been observed in ripening fruit. Maintain coverage through harvest with highly effective rot materials: Indar, Cevya, Orius, Quash, and Tilt (FRAC group 3); and Merivon, Luna Sensation, Pristine, and Quadris Top (FRAC group 11). 

Rhizopus rot on maturing peach fruit. Photo by Amy Andreacchio.

Figure 3. Rhizopus rot on maturing peach fruit. Photo by Amy Andreacchio.

Rhizopus rot has begun appearing in the field in South Jersey as fruit reaches maturity (Figure 3). Rotted peaches look similar to brown rot but are slightly darker, leaky, and the skin slips easily from the decaying flesh underneath. Look for white, fluffy fungal growth (“whiskers”) that turns gray-to-black as fruiting bodies develop. Infection typically occurs through wounds, so minimizing insect feeding, physical injury, and other diseases before harvest is key. Pre- and postharvest treatments, along with rapid cooling after harvest, will help reduce disease incidence. Merivon and Quadris Top 2.72SC are effective materials.  

Insect Update

Oriental Fruit Moth (OFM) trap captures have decreased compared with previous weeks and are below the threshold at most sites. Consider treatment if trap captures are above threshold (>8 moths per trap). A few options for late in the season with low PHIs would include Assail (7-day), Baythroid XL (7-day), Danitol (3-day), Delegate (1-day), and Sevin (3-day). 

Japanese beetles are present in orchards and have been persistent this season, feeding in the tree canopy and on fruit. To prevent losses, include neonicotinoid materials such as Assail (7-day PHI), pyrethroids such as Baythroid (7-day), or premix products such as Leverage 360 (7-day). Verdepryn (IRAC 28, 7-day PHI) is also effective. 

Scale crawlers are active in orchards. See recommendations above for management options. 

Brown Marmorated Stink Bug and other catfacing insects like tarnished plant bug are active in orchards, but injury remains low.  

Lesser and greater peachtree borer trap captures have increased from previous weeks. Where high trap captures have been recorded, growers should begin preparing for post-harvest trunk applications of pyrethroids (Asana or Pounce) or chlorpyrifos, with mid-August through early September generally providing the best timing to target young larvae before they enter the tree. Apply the insecticide thoroughly to the lower trunk, root flare, scaffold crotches, and any canker areas, following label directions. 

Traps

Average Trap Captures in Peach – Southern Counties

 Week   OFM   TABM   LPTB   PTB   BMSB  
5/11/2026   5   10   –   –   –  
5/18/2026   4   20   –   –   –  
5/25/2026   2   20   31   1   –  
6/1/2026   4   46   28   3   0  
6/8/2026   8   13   25   3   0.75  
6/15/2026  5  6  13  3  0.75 
6/22/2026  6  4  23  7  1 
6/29/2026  3  0.2  16  6  2 
7/6/2026  5  0.6  16  4  1.3 
7/13/2026  9  1.4  18  7  3.5 
7/20/2026  8  2.4  12  6  2.5 
7/27/2026  6  2  6  6  8 
8/3/2026  3  2  13  10  1.3 
8/10/2026  4  1  25  10  1 

 

Average Trap Captures in Peach – Northern Counties

  Week   OFM   LPTB   PTB  
5/11/2026   4.4   24   0  
5/18/2026    2.4   16.5   0.2  
5/25/2026   0.7   8.75   0.1  
6/1/2026   1.8   11   0.5  
6/8/2026    0.6   8.5  0.05 
6/15/2026  3.5  9.7  1.2 
6/22/2026  3.4  7.4  1.6 
6/29/2026  2  4.6  1.1 
7/6/2026  1.7  8.5  1.8 
7/13/2026  0.5  2.8  3.7 
7/20/2026  2.1  1.5  2.9 
7/27/2026  4.3  0.9  1.7 
8/3/2026  3.8  1.5  1.2 
8/10/2026  1.5  4.5  2.1 

Blueberries
Insect Update

Spotted-wing drosophila (SWD) trap captures have increased (Table 1), but as harvest activities wrap up, management will shift away from controlling SWD in the field. Sanitation by removing unharvested, culled, or overripe fruit from the field will help to significantly reduce SWD pressure. 

We are keeping a close eye on sharp-nosed leafhopper (SNLH) and scale traps, since this will be your next insecticide spray.  Activity for both has increased (Tables 2 and 3), but not sufficiently to warrant treatment.   

Table 1. Spotted-Wing Drosophila and Blueberry Maggot traps 

  Spotted-wing Drosophila  Blueberry Maggot 
  Atlantic County  Burlington County  Atlantic County  Burlington County 
  Avg  High  Avg  High  Avg  High  Avg  High 
6/6  8.99  35  2.86  7  0.03  1  0  0 
6/12  9.9  46  3.7  25  0  0  0  0 
6/20  10.24  48  8.22  35  0  0  0  0 
6/27  6.96  78  3.6  18  0  0  0  0 
7/3  29.78  273  50.9  81  0.33  27  0  0 
7/10  31.2  130  86.1  177  0.15  12  0  0 
7/18  28.3  110  59.3  125  0.07  5  0.16  1 
7/25  40.22  227  79.1  223  0.07  6  0.06  2 
7/31  52.3  199  58.8  167  0.04  2  0.04  1 
8/8  64.8  341  121  226  0.01  1  0  0 

  

Table 2. Sharp-nosed Leafhopper and Oriental Beetle traps 

  Sharp-nosed Leafhopper  Oriental Beetle 
  Atlantic County  Burlington County  Atlantic County  Burlington County 
  Avg  High  Avg  High  Avg  High  Avg  High 
6/6  1.42  16  1.25  7  5.78  35  2.57  14 
6/12  0.56  12  4.8  46  62  340  47  170 
6/20  0.88  6  1.44  12  411  2025  403  2025 
6/27  0.77  9  0.37  2  243  2025  458  2025 
7/3  1.5  15  0.55  2  466.7  2025  182.7  510 
7/10  1.40  14  0.33  2  396  1970  393  2025 
7/18  0.98  13  0  0  191.1  2025  235  1350 
7/25  1.11  7  0.11  1  64.4  340  136.6  675 
7/31  0.90  5  0.25  2  27.68  132  35.3  85 
8/8  0.85  18  0.3  2  15.6  65  24.3  75 

 

Table 3. Scale Traps 

  Putnam  Terrapin 
  Avg  High  Avg  High 
5/23  36.85  230  1.8  8 
5/29  65.17  352  21.2  41 
6/6  136.25  402  75.25  84 
6/12  164  639  96  202 
6/20  102  288  85  167 
6/27  45  193  32  119 
7/3  41.7  315  27.5  46 
7/10  16.26  74  24.6  61 
7/18  6.06  25  12  24 
7/25  10.5  73  11  24 
7/31  12.6  64  11.3  27 
8/8  20.8  135  15.3  32 
Diseases

Monitoring for black shadow (Figure 4) in blueberry fields showed that in fields where black shadow was observed, the average incidence was approximately 25%, with one field reaching 100%.

Black shadow on blueberry canes. Credit: Peter Oudemans, Rutgers University.

Figure 4. Black shadow on blueberry canes. Credit: Peter Oudemans, Rutgers University.

For recommendations for black shadow management, refer to the 2026 Rutgers Commercial Blueberry Guide. 

Grapes
Insects

Grape berry moth (GBM) trap captures have declined in vineyards. Continue to monitor for damage to bunches and consider treatment when more than 10-15% of the bunches show berry webbing and GBM larval feeding injury. Be mindful of the pre-harvest interval as we approach harvest. See the Commercial Grape Pest Control Recommendations for New Jersey for management options. 

Spotted-wing drosophila male adult on ripening grape.

Figure 5. Spotted-wing drosophila male adult on ripening grape.

Spotted lanternfly (SLF) adults are present in vineyards. As we approach September, adult migration into vineyards will increase, at which point we consider applying materials with long residual efficacy. See this previous Plant & Pest Advisory post on Management of Spotted Lanternfly in New Jersey Vineyards.  

Spotted-Wing Drosophila male adult flies are being trapped in vineyards in southern counties (Figure 5). Monitoring efforts have shifted to grapes as veraison progresses and ripe fruit becomes vulnerable to infestation.

Diseases

Disease management continues to focus mainly on downy mildew, powdery mildew, bunch rot, and black rot. Outbreaks of anthracnose fruit rot have also been observed (Figure 6). Refer to the NJ Commercial Grape Production Guide for more information on disease management options.

Anthracnose fruit rot on grapes.

Figure 6. Anthracnose fruit rot on grapes.

Pre-Harvest Drop Control and Harvest Management for Apples

For growers interested in using products to control pre-harvest drop, particularly on Early/Mid-Season apple varieties, now is the time to consider applying them.  This is a valuable consideration particularly this year for retaining high value varieties such as early season Honeycrisp.

As apples mature they produce the hormone ethylene.  Ethylene induces stem loosening which results in pre-harvest drop of apples.  Luckily there are several tools that when applied at optimal times can aid in the management of pre-harvest drop of apples.

*Prior to the application of any product though, remember to read and follow the product label, because the label is the law.

 

Plant Growth Regulator Options for Apple Harvest Management:

Active Ingredient: AVG (aminoethoxyvinylglycine)

ReTain 

This product slows starch disappearance, fruit softening, stem loosening and red color development.

Benefits include:

Expansion of the harvest window by minimizing pre-harvest drop and retaining fruit firmness.

Enhancement of fruit size since fruit are given more time to hang onto the tree.

Color enhancement due to exposure to improved weather for fruit coloring (warm sunny days and cool nights).

Application Timing: For maximum efficacy ReTain must be applied 4 weeks prior to harvest.

Single Pick Varieties

For single pick early season varieties, establish the ‘usual’ harvest time for the variety, and if the season is running early adjust the date earlier (accordingly).  Once an accurate estimated harvest date is established count back four weeks.  This timepoint plus 7 days is the spray window for ReTain for that variety.

Calculate the spray timing for later season, single pick varieties in a similar way.  However, later varieties generally do not need harvest date adjustment due to seasonal variation in the same way early season varieties do.

Multiple Pick Varieties i.e. Gala and Honeycrisp

Spray timing for these varieties is 7 to 14 days prior to harvest/first pick.  Note that ReTain will not affect the first harvest/pick but will provide stop drop control for later season picks.

Variety Response to ReTain and Rate:

Variety response to ReTain and rate.

*When applying ReTain be sure to include 100% Organosilicate surfactant @ 12 ounces/100 gallons.

*Ensure there will be 6 hours of drying time after the application.

 

Active Ingredient: 1-MCP (1-Methylcyclopropene)

Harvista

Much like ReTain this product slows starch disappearance, fruit softening, red color development and pre-harvest drop.

Application Timing: It should be applied within 3 days prior to harvest, much closer to the time of harvest than a ReTain application.  This product is a bit more complicated to use in that it must be applied via a proprietary in-line injector system.

 

Active Ingredient: NAA (naphthaleneacetic acid)

NAA (Multiple Formulations)

This product provides what is considered a rescue treatment for control of fruit drop.

Application Timing: Optimum timing of spray is a couple days prior to harvest, when the first fruit begins to drop.

One application of 10 ppm NAA will provide 7-10 days of drop control.

A two-part spray of 10 ppm, one a couple days prior to harvest and a second 5 days later will provide 10-14 days of drop control.

Keep in mind it takes ~2-3 days for the sprays to take effect.

*Apply with a nonionic or organosilicate surfactant.

*Spray when the temperatures are in the mid 70’s.  If the temperature is too hot, fruit ripening can be accelerated.

 

Table 1. A quick comparison of compounds registered as stop drops.

Parameter ReTain Fruitone, PoMaxa, or Refine Harvista
Active Ingredient AVG NAA 1-MCP
What Is Blocked Ethylene production Stem loosening Ethylene action
Drop Delay (Approximate) 10–14 days 5–7 days 10–14 days
Fruit Ripening Slowed Advanced Slowed
Fruit Color Delayed No effect Somewhat delayed
Fruit Softening Delayed No change or advanced Delayed
Applied (Relative to Drop) 2-4 weeks before Just prior to Just prior to
Rescue Option? No Yes Yes
Days to Take Effect >7 ~2 ~2
Split Sprays Helpful Yes Yes Not applicable
REI 12 hours 48 hours 4 hours
PHI 7 days 2 days 3 days

Cited from 2024-2025 Penn State Tree Fruit Production Guide page 79.

 

For additional details on utilizing plant growth regulators for harvest management read:

2025/2026 New Jersey Commercial Tree Fruit Production Guide Chapter 10. https://njaes.rutgers.edu/pubs/publication.php?pid=e002

Apple PGRs – Prevention of Preharvest Drop in Apple Orchards – Production and Harvesting – Fruit – Forage and Food Crops (psu.edu)