Vegetable Notes 2026 Vol. 38:5

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Crop Conditions

Feels like we’ve been through all the seasons at least once this year and it’s only the first week of May. Winter turned to summer in April, then back to fall, then another summer and another winter, and here we are finally at spring! What do they say, if you don’t like the weather, wait a minute? After another half inch of rain this week, the dust has briefly settled with more rain forecast for the weekend, giving folks a window to get more plants in the ground. Potatoes and onions are in, garlic is shooting up, and greenhouses are bursting at the seams with transplants, as well as bedding plants—seedling sales have become an important part of the crop plan for many farms, with Mother’s Day this weekend marking a big milestone for home gardeners to start their planting, as well as shop for tulip bouquets!

Pest Alerts

Alliums

Allium leafminer (ALM) adults have now emerged and are laying eggs in allium leaves in MA. While this pest has typically been most prevalent in western parts of the state, a recent report from northeast MA indicates that ALM’s range has continued to expand to new areas. Scout perennial chives and overwintered onions for rows of light-colored circular or horseshoe-shaped egg-laying scars to monitor ALM presence in your area. Let us know if you find signs of ALM east of Worcester County by sending a photo of the egg-laying scars and where you found them to umassveg[at]umass[dot]edu (umassveg[at]umass[dot]edu)!

Adults will continue to be active for 5-6 weeks after emerging. Row covers will exclude adults if installed before flight begins. Insect netting that doesn’t trap heat reduces the risk of heat stress in sensitive crops. Reflective mulch can reduce damage severity but will not successfully eliminate the pest without other controls.

Insecticides can be used to target adults and larvae once egg laying begins in your area. Allium leaves are waxy and sprays will bead up and roll off of the leaves, so unless labels prohibit it, always include a surfactant with pesticide sprays to limit runoff and maximize uptake. Trials from Penn State Extension have shown that effective control can be achieved with applications of dinotefuran (e.g. Scorpion, Venom), cyantraniliprole (Exirel), and spinetoram (Radiant), starting up to 2 weeks after feeding/oviposition marks are detected. All of the above materials have systemic or translaminar activity and will be effective against larvae. Contact pyrethroids including Mustang Maxx and Warrior will also be effective against adults (not larvae). Research from Cornell University has shown that applications of Entrust + M-Pede are highly effective. Organic growers should apply Entrust at 6 oz/A + M-Pede at a 1-1.5% v/v solution, two times, 2-4 weeks after first detecting allium leafminer in a crop.

Basil

Sunburn is a common issue on basil seedlings at this point in the season. When plugs are moved from a crowded tray to a pot for sale, or if seedlings are moved out of a shade-clothed greenhouse to harden off during a particularly sunny period, the sudden increase in exposure to sunlight sometimes causes sunburn on leaves. Sunburn can look similar to downy mildew symptoms but sunburned leaves will not develop fuzzy sporulation. Ensure that seedlings are given adequate time to harden off and avoid leaving pots in direct sunlight for prolonged periods to prevent this. 

Brassicas

Flea beetles are active on spring brassica plantings. Adults emerge from overwintering sites in forested field borders and chew tiny holes in leaves of cruciferous plants, killing seedlings and weakening larger plants. Insect netting or kaolin clay (Surround) can provide a physical barrier to reduce damage to young plants, and both conventional and organic insecticides are available for control. See the article in this issue for more information about managing this pest. 

Cabbage root maggot adults are expected to be active and laying eggs at the base of young brassica plants across MA based on growing degree day (GDD) models (see tables 1 & 2). Larvae will hatch and enter the soil to feed on the roots of susceptible crops. This causes tunneling damage on root crops and stunting or plant death in heading and leafy crops. Use the NEWA degree day calculator to predict when they will emerge in your area and scout for 3 mm-long, white, oblong eggs at the base of plants. 

If applied before adult flights, row covers are effective at preventing egg-laying. Delaying planting until late May or early June when fewer adults are active can also prevent major infestations. If maggots are present, cultivating vigorous brassica crops so that soil is brought up around the stem encourages adventitious root formation which can compensate for root loss. 

Soil drenches of Coragen (chlorantraniliprole) or Verimark (cyantraniliprole) are labeled for leafy and root brassica crops and may be applied at planting. Radiant (spinetoram) and Entrust (spinosad, OMRI-listed) are both only labeled for use on leafy brassicas and may be applied at planting and in up to 2 additional applications. Other labeled materials include bifenthrin (Capture, Sniper LFR, Brigade – head and stem brassicas), diazinon (specific crops only), Mustang Maxx (root brassicacs), and AzaGuard (all brassicas).

See our article from last year for more information on managing this pest. 

Imported cabbageworm adults (cabbage whites or ICW) are flying now and will start laying eggs in uncovered brassicas soon. Eggs are oval and ~3 mm long, laid singly, on-end, on the undersides of brassica leaves. ICW is the earliest of the brassica caterpillar pests—it overwinters as pupae in the field, whereas the other brassica caterpillar pests (diamondback moth, cabbage looper, and cross-striped cabbageworm) usually don’t overwinter in the Northeast. ICW caterpillars will start hatching in a few weeks. They are green and slightly fuzzy, and camouflage very well along the midrib of brassica leaves. Row cover will prevent egg-laying in crops. If you plan to use pesticides, make sure you have them on-hand now. Labeled conventional products include spinosyns (e.g. Radiant), pyrethroids (e.g. Warrior, Mustang, many others), diamides (e.g. Vetica and Coragen for soil or foliar applications or Exirel and Verimark for soil applications only), Proclaim, Avaunt, and Torac. Diamide products are more expensive but are systemic, have long residuals, and will also protect against flea beetles and cabbage root maggot. Bt products (e.g. Dipel, Xentari) are the most effective OMRI-listed materials. Use a spreader-sticker to help materials adhere to waxy brassica leaves.

Nightshades

Aphids are active in high tunnel tomatoes & peppers, especially in tunnels that were started earliest in the season. Scout regularly for colonies and hotspots, checking the undersides of leaves and looking out for signs of infestation like honeydew and sooty mold. Preventative biological controls should be introduced now and maintained through the end of the season, as they cannot keep up with aphid population growth if those populations are given time to ramp up. Parasitoid wasps are a reliable biocontrol option for this purpose. Make sure to identify aphids (green peach aphid, foxglove aphid, and potato aphid are common in tunnels) and use the correct wasp species for the aphid species you are targeting. Follow release rates recommended by your supplier for the best chances of success.

Multiple/Miscellaneous Crops

Seedcorn maggot: We are past peak flight for seedcorn maggot across the state (see tables 1 & 2) and crop damage is likely still occurring in large-seeded crops like peas, beans, and sweet corn. Many growers in MA and beyond reported heavier-than-usual infestations this year on unprotected crops, especially onion transplants. This may have been caused by a sudden onset of warm temperatures which prompted rapid emergence of adult flies and a sharp peak in egg-laying that coincided with an unfortunately-timed period of rainfall. Maggots feed on the roots of seedlings, causing poor stand and killing most young, infested plants. Larvae develop over 2-3 weeks then pupate, resulting in a second generation of the pest with adult peak flight at around 1080 GDDs base 40°F. Although this generation is not typically as damaging as the first generation, replanting another susceptible crop in the same or nearby fields carries the risk of reinfestation by the second generation of maggots. Onions planted in the next few weeks also face the risk of infestation by onion maggot flies, which have a peak flight at 735 GDDs base 40°F. Plan your timing around these peak flights or use preventative insecticides or row cover to protect susceptible crops. 

Table 1. GDD for peak flight of key maggot fly pests (Base T = 40°F)

Peak Flight	Seedcorn Maggot	Onion Maggot	Cabbage Root Maggot
1st gen	360	735	452
2nd gen	1080	1752	1261
3rd gen	1800	2975	2176
4th gen	-	-	3014

Table 2. Growing degree day (GDD) accumulation, Jan. 1- May 6, 2026

Weather Station Locations	GDDs base 40°F (Cabbage, onion, & seedcorn maggots)
Western MA
Deerfield	476
South Deerfield	516
Easthampton	510
Chicopee Falls	566
Westfield Arpt	531
Central MA
Leominster	470
Northbridge	493
Worcester	437
Eastern MA
Bolton	473
Stow	464
Lawrence Arpt	446
Ipswich	409
East Bridgewater	462
Boston	492
New Bedford Arpt	411

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Berry Blast

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Small fruit crops have progressed from dormancy into active early-season growth. The April 20–21 cold event raised concerns for blueberry growers in some locations. Injury has been variable and is still being assessed across the state. Warmer temperatures at the end of April pushed all berry crops into more advanced growth stages, and management strategies are shifting as the season ramps up. As we move into May, the main concern is the combination of exposed green tissue, bloom development, rainfall, humidity, and degree day accumulation. Insect and pathogen activity will continue to increase as temperatures rise. When making management decisions, be sure to base it on your scouting and monitoring data, the crop stage, field history, and weather in your location.

Strawberries 

Strawberries came through April with new leaves emerging and flower buds developing within the crown. Most fields were not yet in full bloom during the April cold event, which reduced the risk of widespread blossom injury, but any advanced flowers should still be checked for black or brown centers. As May progresses, Botrytis gray mold becomes more of a concern as fields enter bloom, especially if rain and prolonged humidity line up with open flowers. Continue scouting for weak crowns, uneven growth, drainage problems, leaf diseases, and any insect activity as temperatures increase. Focus on keeping the canopy dry and making scouting-based decisions before any pesticide application.

Brambles 

Brambles moved from dormancy into rapid new shoot growth during April. Some cold injury may still become visible as damaged shoot tips or buds fail to expand normally, so avoid making aggressive pruning decisions until live and dead tissue can be clearly identified. In May, insects and diseases will begin to arise, so management should be focused on thinning canes for air flow, improving drainage, sanitation, and early detection of cane diseases and insect pressure.

Blueberries 

Blueberries showed the most noticeable change during April, with early varieties moving from bud swell to early bloom by May. The April 20–21 cold event occurred while many plantings were around tight cluster, but early varieties and low areas still may have been affected and should be checked for frost damage. High winds may have amplified the frost effect. Cut flower buds lengthwise and check for brown, black, water-soaked, or collapsed internal tissue. See this resource on blueberry bud stages and low temperature thresholds from Michigan State University. Currently, Patriot is at the early bloom stage in some locations, while Chandler is closer to tight cluster, so disease risk moving forward will vary by cultivar and location. For May, mummy berry remains the main disease concern with Botrytis becoming more important towards bloom. Pollinator activity has begun; avoid unnecessary insecticide applications during bloom and keep pollinator safety in mind with all spray decisions. 

Grapes 

Grapes stayed relatively quiet through much of April, but early cultivars are now beginning to move. Frontenac has reached bud burst in observed locations, while many other cultivars remain behind. As May progresses, Phomopsis cane and leaf spot become the main diseases to watch for. Rain events during early shoot growth can increase infection risk, so Frontenac and other early-cultivars should be scouted first. Continue checking for grape flea beetle injury this month, and scouting for spotted lanternfly egg masses on vines, trellis posts, equipment, and nearby host material.

Asparagus Report

To say the asparagus season has been a roller coaster ride so far is an understatement!  We started picking asparagus on April 18, which by far is the earliest I can ever recall. Normally when we are asked when asparagus harvest starts, we mention May 1 with some years a few days earlier and other years a few days later. But April 18 is unprecedented! The following Monday brought temperatures in the low 30s/upper 20s and we noticed some frost damage to some of the spears coming off the fields. But the devastating killing frost occurred the next morning with temperatures in the range of 23-25°F. Any spears above the ground were destroyed! It was especially devastating because there were so many spears just breaking the ground. The biggest question we had was how the asparagus would respond to the killing frost. It would be 8 days before we started picking again and much to our pleasant surprise, the fields came back amazingly well and we’ve had 3 of our historically largest harvest days since we resumed picking! We are now wondering if this will hold up and if there might be some effects that we might see later on in the season from the frost. Time will tell, but we could not have asked for a better rebound from the frost. And I will add that historically frost remains a concern for the first 2-3 weeks in May to the asparagus crop.

--written by Tom Smiarowski, D.A. Smiarowski Farm in Sunderland, MA, and formerly of UMass Extension

Flea Beetle Management

Flea beetles have emerged from their overwintering homes in the shrubby or wooded areas surrounding fields and are feeding now on spring brassica plantings. Controlling flea beetles can seem like a losing battle, but we have seen real success on farms that have taken an integrated approach to management. The most impor­tant steps to reducing the population size and damage caused by flea beetles seem to be breaking the cycle (rotating spring crops as far as possible from overwinter­ing sites near last year’s fall crop), and controlling early season outbreaks using something like a trap crop or a “push-pull” approach to prevent the problem from spiraling out of control within the season or from building up to unmanageable levels over the years.

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Life Cycle

There are two species of flea beetle that feed on brassica crops. The crucifer flea beetle (Phyllotreta cruciferae) is uniformly black and shiny, while the striped flea beetle (Phyllotreta striolata) has two yellow stripes on its back. Both are about 2 mm in length and hop away when disturbed. These two species only feed on brassica crops; flea beetles found on corn or solanaceous crops are different spe­cies. Though they prefer the tender leaves of Brassica rapa and B. juncea crops such as arugula, tatsoi, mizuna, bok choi, and mustard, they will also feed on the more waxy B. oleracea crops such as broccoli, cabbage, kale, and collards. Their feeding damage—small, round holes on leaves or leaf margins, which can coalesce or expand to form large holes as leaves mature—can kill seedlings outright, delay maturity, and re­duce yield and marketability of older plants. The adults that are ac­tive now will mate and lay eggs in the soil, and larvae will hatch in 11-13 days. Larvae will feed on the root hairs of brassica crops but do not cause noticeable damage. After about 3 weeks, the larvae will pupate.  They will emerge after another week, around mid-June, as the next generation of adults. This cycle repeats itself and a second sum­mer generation emerges in late July to feed on fall brassica crops before moving out of the field to forested areas for the win­ter. Flea beetle generations usually overlap over the course of the growing season, meaning there is rarely a lull in flea beetle activity. 

Click on images for description and to expand.

Row Covers

Floating row cover or insect netting provides the most effective protection from flea beetles, especially in spring and early summer. Although this practice is expensive in both materials and time, it can provide up to 100% mechanical control of flea beetle if used correctly. Insect netting, such as Proteknet, Biothrips, and Filbio, are available in a range of mesh sizes and can be used to protect against a variety of pests in addition to flea beetles. These trap in less heat and allow for greater air circulation than spunbonded row covers, though for early spring crops, the additional warming benefit of traditional row covers of various weights may be preferred. No matter which cover you choose, it is critical to seal the edges immediately after planting to make sure you exclude the beetles. Flea beetles can fit through small gaps in netting, not to mention the large holes and tears that often develop in row cover over time. Fortunately, hoops are not needed on brassica crops, but management is still time-consuming because the cover must be removed for cultivation. Re­place it as soon as possible to avoid letting beetles in. 

Chemical Control 

Maturing plants should be scouted frequently. When plants are young, an average of 1 beetle per plant or 10% average leaf damage is a reasonable threshold for chemical intervention. Several synthetic pyrethroids (Group 3A), carbamates (Group 1A), neo­nicotinoids (Group 4A, either as foliar or soil drench), and diamides (Group 28) are labeled for flea beetle in brassicas. Avoid using insecticides from the same IRAC group repeatedly over multiple generations or in both soil and foliar applications. 

Systemic insecticides can provide longer-term control, though beetles may still be seen when scouting as they will continue to come in from field edges and will not be killed until they consume some of the plant. Diamide prod­ucts (Exirel and Harvanta for foliar applications, Veri­mark for soil), are systemic and provide control against flea beetles as well as other brassica pests like caterpil­lars, cabbage aphid, and, if applied to the soil pre-plant, cabbage root maggot. Be aware that systemic insecticides may have longer days-to-harvest intervals. 

Another option that has recently been introduced to the market is Incipio, a broad-spectrum insecticide with the active ingredient isocycloseram (IRAC Group 30) that is formulated for brassicas, cucurbits, fruiting vegetables and leafy greens and is labeled for foliar application. Although it is not a systemic insecticide, it has translaminar activity that provides some residual control. 

See the New England Vegetable Management Guide for more information about chemical management options.

For organic farmers, the choice of effective chemistries is limited to spinosad (Entrust), pyrethrin (Pyganic), and kaolin clay (Surround). Entrust provides the best control; it works primarily by ingestion and remains active on the leaf surface for some time after application. Pyganic is a contact insecticide and is deactivated by sunlight, so it does not provide any residual control, but it can provide short-term knockdown effects. Surround is kaolin clay that coats the foliage, which flea beetles find unappealing. It must be reapplied as the plants grow or after rain. Growers often hesitate to use Surround because of difficulty mixing and spraying—some growers have found that using a masonry or sheet-rock drill to mix up the material in a 5-gallon bucket before adding to a backpack sprayer works to get the clay into suspension. If you want to apply Surround using a tractor-mounted sprayer, you must have mechanical agitation. Otherwise, the material will not go into suspension and will clog up your nozzles. It is probably worth figuring out how to do this if you struggle with getting your early season transplants to survive the onslaught of flea beetles, and it can also be useful in protecting cucurbit transplants from striped cucumber beetles, which vector bacterial wilt.

Trap Cropping

Take advantage of the flea beetles’ preferences for particular brassicas by using the preferred species or varieties as a draw. Their numbers will concentrate in the more attractive plants, where they can be managed with an insec­ticide application, protecting the main crop and reducing spray area and time. A border or even a middle row planted to Brassica rapa or B. juncea crops such as komatsuna, tatsoi, mizuna, bok choi, or mustard has been shown to reduce numbers and feeding damage on less preferred B. oleracea crops such as broccoli, cabbage, or traditional kale (e.g. ‘Winterbor’ types). Red Russian kale (B. napus) and lacinato kale (B. oleracea) seem to be of intermediate attractive­ness. To make it work, here are some tips:

• Make sure the trap crop is established before the main crop (the one you are trying to protect) or is at least as mature (e.g. transplanted same day). Direct-seeded crops can be used around transplants if seeded 7-14 days earlier.
• Use a fast-growing, vigorous cultivar for the trap crop.
• Use a border crop to prevent beetles from moving farther into the field. Traps at ends of rows help make a com­plete perimeter, which stops beetles coming from all directions. Interior trap crops, which are beds planted within the field of the main crop, also can act as a ‘sink’ within the field.
• Spray only the trap crop to kill the accumulated beetles, and to avoid having to spray the main crop. You also want to keep the trap crop healthy enough to do its work, and potentially be harvestable as well—you may need to fertilize, re-seed, or otherwise maintain this trap crop because if it gets too ragged, the beetles will not enjoy feeding on it and will move back into your main crop. Use a longer-residual product, if possible.
• Combine with a repellent on the main crop, e.g., coat the main crop with Surround WP and use a trap crop as part of a “push-pull” system.

--UMass Extension Vegetable Program

Calculating Fertilizer Applications

It can feel overwhelming to calculate fertilizer needs for each of the many crops and fields on your farm. Every year we help growers, both new and seasoned, to make these calculations. If you follow the steps outlined in this article, the process should get easier over time. Our recommendation is always to make these calculations to determine what you should add in an “ideal” setting (if fertilizer was free and easily available and you had all the time in the world), and then figure out what you can realistically add to your fields, based on what is available and economical. Keep records on what you apply so that you can make educated changes to your applications if you see nutrient deficiencies in your crops. Here are the steps to follow, with details below:

1. Work from a soil test. A typical standard soil test will report macro- and micronutrient levels and soil pH. Some labs will automatically report soil organic matter (SOM) levels, and at other labs (including the UMass Soil Lab) you need to specifically request for SOM to be tested. The UMass Soil Lab reports provide the soil nutrient level and optimum range of each nutrient in parts per million. Macronutrient (phosphorous, potassium, calcium, and magnesium) levels are also reported as very low, low, optimum, or above optimum. Because nitrogen is so mobile and ephemeral in soils, nitrogen is not routinely tested for in standard soil tests, and instead, nitrogen applications are made solely based on crop need. To test plant available nitrate during the growing season, you can take a pre-sidedress soil nitrate test. We highly recommend having your soil tested at one of the New England state soil labs, as the tests run at these labs are specific to New England soils.

Note for high tunnels: If you are calculating fertilizer applications for a high tunnel, we recommend taking both a standard soil test and a saturated media extract test. The standard test procedure extracts reserve nutrients and reports the nutrient levels that will become available to plants as the season progresses. In the warm, well-watered high tunnel environment, crops will immediately grow very quickly, so it’s also important to know what nutrients are immediately available to those plants. This is measured using a saturated media extract (SME) test. For long-term high tunnel crops like tomatoes, cucumbers, or peppers, use both the standard soil test and the SME to plan nutrient applications in the spring, and then take leaf tissue samples monthly to inform fertigation or side-dressing during the season (more information on tissue testing here). The UMaine Soil Lab offers a Long-Term/Combined High Tunnel Package that includes both a standard and SME test and corresponding recommendations.

2. Find nutrient recommendations for your crop. If you indicated a crop on your soil test submission, you will receive nutrient application recommendations based on the crop need and the soil test results. For commercial vegetable growers, those recommendations will be in lbs/acre; for home gardeners, they will be lbs/100 sq. ft. If you don’t indicate a crop on your soil test form, you can easily look up crop-specific recommendations in the crop sections of the New England Vegetable Management Guide. In this example, we’ll make a fertilizer plan for broccoli, and we'll work from the nutrient recommendations below that are from the Cabbage, Broccoli, Cauliflower, and other Brassica Crops section.

For most crops, these tables are split between an up-front application (broadcast and incorporate) and a sidedressing application a certain number of weeks after seeding or transplanting. All of the P and K that a crop needs can be put down up front, before planting, because P and K will stay in the soil and remain available for when the crop needs them. Depending on the N source, N applications can be applied 100% pre-plant or split between pre-plant and sidedressing. Inorganic forms of N (e.g. urea) will leach quickly from soil, so any N you put down pre-plant that your crop doesn’t take up relatively quickly will leach out, along with the money you spent on it! Organic forms of N are released slowly by microbial activity throughout the season, so if you are using an organic form of N, you can apply all N up front, along with P and K.

Broccoli N recommendations are 100 lbs/A pre-plant and 60 lbs/A four weeks after transplant (circled in yellow). We’ll do our calculations using Kreher’s 5-4-3 chicken manure, which is an organic amendment that will release N slowly, so we will apply the full 160 lbs/A up front.

P and K recommendations are based on your soil test results. In our example soil test, our P levels are optimum, so the recommendation, circled in red, is to add 50 lbs P/A. (New England state soil tests are based on a “build and maintain” model, which recommends you add nutrients even when the level in the soil is optimum, so that soil reserves are not depleted.) In our example, K levels are low, so we should add 125 lbs K/A (circled in blue).

3. Calculate nitrogen credits. Manure, compost, some cover crops, soil organic matter, and sod all contain N that can be credited towards your total N needs for the season. The recommendation entered at the top of Table 1, below, is the preplant nutrient recommendation from step 2, and the following paragraphs will explain how the credits are calculated:

   Table 1. Nutrient credit calculations
   Recommendations (from step 2)	N 160 lbs/A	P 50 lbs/A	K 125 lbs/A
   Credits
   Manure	-	-	-
   Compost	-	-	-
   Cover crop	10	-	-
   Soil organic matter	40	-	-
   Sod	-	-	-
   Total credits	50	0	0
   Nutrients needed	110	50	125

Manure and compost: Like soil, manures and composts can be analyzed by a soil testing lab to determine the nutrient content, pH, C:N ratio, and other important characteristics. Compost and manure analysis is available through the Penn State and UMaine soil testing labs. If testing your organic amendment is not possible, approximations can be found in the Manure section of the New England Vegetable Management Guide.

Cover crops: When a cover crop is tilled in, N stored in the leaves and roots is released and much of it will be available for your summer and fall crops. Nitrogen release from cover crops peaks 4-6 weeks after incorporation. In the spring, the soil doesn’t warm up fast enough for the microbes to release the N before the main crop needs it, so don’t include N credits from cover crops for early spring crops. Sod also contributes some N when it’s plowed under to start production in a new field. Table 2 shows estimates of N contributions from certain cover crops. These numbers can vary widely, based on the quality of the cover crop stand and time of incorporation. If you’re interested in learning more, the SARE publication Managing Cover Crops Profitably is a great resource.

Soil organic matter: Soil organic matter (SOM) contains N that becomes available for plant uptake slowly throughout the season as it is released through microbial activity. The general rule of thumb in MA is: credit yourself 10-20 lbs/A of plant-available N per 1% SOM, capped at 4% or 40 lbs/A. The amount of N released from SOM increases with soil temperature, so numbers may vary between New England states.

Our example soil test results show SOM content of 4.4%, and we’ll say that we incorporated a buckwheat cover crop. The following credits are entered into Table 1:

• Buckwheat cover crop: 10 lbs N/A
• Soil organic matter: From our example soil test, our field has 4.4% SOM. 4.4 x 20 lbs/A = 88 lbs N/A, but SOM credits max out at 40 lbs/A, so we'll credit ourselves 40 lbs/A.

In Table 1, after subtracting our nitrogen credits from our total nitrogen needs, we now need to apply only 110 lbs N/A.

4. Choose your fertilizer. This choice can be made based on many different factors, including:

• What fertilizer you already have on hand
• Price
• Application equipment (some materials are easier to spread with certain types of spreaders)
• Availability of materials from local distributers
• What materials meet your nutrient needs most closely

We’ll use Kreher’s 5-4-3 chicken manure for this example. “5-4-3” means that the material contains 5% N, 4% P, and 3% K.

5. Calculate how much fertilizer you need to apply to meet your pre-plant N needs.

We need to apply 110 lbs/A N (from Table 1) and our fertilizer is 5% N: 110 lbs/A nitrogen ÷ 0.05 = 2,200 lbs/A 5-4-3

In order to apply 110 lbs/A of N, we need to apply 2,200 lbs/A of 5-4-3.

6. Calculate how much P and K that amount of fertilizer will add.

Kreher’s 5-4-3 is 4% P and 3% K.

• 2,200 lbs/A of 5-4-3 x 0.04 = 88 lbs/A P

Total P needed (from Table 1) = 50 lbs/A. Our application of 5-4-3 will apply 88 lbs/A of P, so we are actually overapplying P and do not need to apply any more.*

• 2,200 lbs/A of 5-4-3 x 0.03 = 66 lbs/A K

Total K needed (from Table 1) = 125 lbs/A.

125 lbs/A – 66 lbs/A = 59 lbs/A K

Our application of 5-4-3 will apply 66 lbs/A of K, so we need to put down an additional 59 lbs/A to reach our total K need.

7. Calculate how much additional fertilizer you need to reach your other nutrient needs.

We need to apply an additional 59 lbs/A of K. We’ll use potash (0-0-50) to meet that need.

59 lbs/A K ÷ 0.5 = 118 lbs/A potash.

In order to apply 59 lbs/A of K, we need to apply 118 lbs/A of potash.

Now we have ideal application rates for both of our fertilizers:

• 2,200 lbs/A Krehers 5-4-3
• 118 lbs/A potash

And you’re ready to brew a big pot of coffee and do the same math for your remaining fields and crops!

*It is easy to overapply P with a blended fertilizer like this, which is relatively high in P compared to N. Overapplying P by large amounts and over long periods of time can lead to phosphorous runoff and leaching and environmental contamination. We used 5-4-3 for this example because it's commonly used, but to more accurately meet the crop nutrient needs and avoid overapplying P, organic growers can instead apply feather meal (13-0-0), bone char (0-15-0), and potash (0-0-50).

--Written by G. Higgins, with many thanks to Becky Maden of UVM Extension

News

MDAR Grants Currently Open:

Urban Agriculture Program: To support commercial urban food production and community-based food production in the Commonwealth. Eligible applicants include municipalities, nonprofit organizations, public or non-profit educational or public health institutions, and established urban farmers with more than 3 years of commercial urban farming experience. Examples of project priorities include soil management; land acquisition; equipment; marketing, distribution, and transportation; green infrastructure; innovative growing technology; urban to rural bridge; and organic farming support. 

Applications due: Monday, May 18, 4pm Contact: Rose[dot]Arruda[at]mass[dot]gov (Rose[dot]Arruda[at]mass[dot]gov), 617-851-3644.

Food Ventures Program: To increase access to healthy, affordable food options and improve economic opportunities for low to moderate income communities. The MFVP will provide funding through grants to support food ventures, sited primarily in or near communities of low or moderate income, including Gateway Cities and rural communities. The MFVP will help implement goals of the Massachusetts Local Food Action Plan and contribute to the financing needs of local Massachusetts food enterprises.  Key areas for investment include: food processing infrastructure to meet the needs of the expanding local food system; improved distribution systems to support opportunities for equitable access to fresh local food; and retail outlet strategies that enhance access to healthy food. 

Applications due: Thursday, May 28, 4pm Contact: Rose[dot]Arruda[at]mass[dot]gov (Rose[dot]Arruda[at]mass[dot]gov), 617-851-3644.