Improving Production Practices for Three Niche Crops in Response to Shifting Climatic Opportunities

Sweet Potato

In-Season Assessments:
Plant population per variety at planting ranged from 5 - 60 plants per variety. Sweet potatoes commonly shrivel after planting while they set their roots. Accurate assessment of surviving stand needs to wait until 2-3 weeks after planting. We took that assessment on June 25 and observed excellent survival. The July plant health assessment revealed one more 'Bonita' plant had survived than we thought on June 25.  Additionally, a section of soil had washed out from under the plastic in the middle of the 'Luminance' planting due to torrential rains. Soil was pushed back up against the plastic bed edge to secure the plastic.  Some minor hail had also struck the foliage during that heavy rain event, causing very  minor, occasional damage evenly dispersed across varieties. There was also some Japanese beetle feeding damage of very minor severity, concentrated on the south end of the trial. No appreciable rodent damage was observed. We believe the excellent weed control and clean fallow strip on either side of the trial prevented rodent damage. Ground cover assessments revealed that 'Radiance' was less vigorous than any other variety and 'Luminance' also lagged in foliar growth. 'Bellevue' had the best canopy cover six weeks after planting. 'Bonita' was not assessed due to evaluator error.   

Harvest occurred on two dates. 'Bellevue' and '18-100', the two shorter day varieties, were harvested at 100 days on Sept 16 (1750 GDD base 50) following maturity sampling of two plants per variety.  As digging progressed through these two varieties, we discovered that the maturity was more variable than the samples had indicated. It is our belief that these varieties would have benefited from at least another week in the field and probably needed another 50-100 degree days to evenly reach maturity. Note that we made the decision to harvest only a portion of the '18-100' were harvested because we had obtained a sufficient sample size. The remaining, longer day varieties were harvested at 119 days on October 5. The crop had accumulated 1990 GDD base 50 by Oct 5. 

'Luminance' had thin skins and scuffed very easily during harvest. It also produced many long, stringy tubers that were prone to breakage during mechanical lifting and digging despite efforts made to keep the tubers in one piece. 'Vermilion' and 'Radiance' also produced a lot of stringy tubers. '18-100' produced on-shape tubers that had more lenticels than the other varieties that were occasionally pronounced enough to impact marketability. The variety also grew slight ridges that spiraled down the length of the potato. After consulting with the breeder, these are believed to be physiological responses to having sat in overly saturated soil for too long. We presume this happened following heavy and consistent rainfall in July.  'Bellevue' and 'Bonita' both produced nice sets of tubers. 'Bonita' displayed a strong tendency to make one set at the crown and another set at the bottom of the slip. The several inch gap between the two sets made it easy to underestimate how deep the second set was in the soil when we began digging the variety. It would have benefitted from a deeper loosening of the soil, had the equipment been capable. 

The crop was graded into USDA grade standard #1 marketable potatoes, NY marketable grade (smaller than USDA but still salable in local markets), undersized unmarketable, stringy off-type cull (long, twisted, potatoes >1" diameter), and rot cull on Nov 20, 2023.

The varieties harvested on Sept 16 exhibited far less rot after curing and storage than those harvested Oct 5. This is thought to be caused by several compounding factors, listed in order of importance:

1. The varieties harvested Oct. 5 had more breakage and skin damage going into harvest because of undesirable varietal characteristics (thin skins, stringy tubers). 
2. While the curing chamber did a better job of maintaining temperature and humidity than the greenhouse bench, it also had poorer air circulation and allowed for some condensation on the plastic surfaces. More airflow was likely needed to improve curing conditions and discourage rot.
3. Stacking the crates in the curing chamber and created the opportunity for rot organisms to drip down from one crate and variety to the next with any condensate.
4. 'Bonita' has been shown in previous NY work to be prone to rot. 

Fresh market direct retails may choose to sell sweet potatoes may be sold by the piece or by the pound.  For that reason, above we present the grade distribution of the sweet potato varieties as determined by the percent of total tubers produced per variety (top) and by the percent of the total weight of tubers produced per variety (bottom). Using the percent data instead of the raw counts and weights allows for direct comparison of one variety to another by removing the effect of varying plant populations. 

Under both measurements, 'Bellevue' and '18-100' produced the most marketable tubers with the lowest amount of rot and stringy culls even though they were harvested prematurely. Had they been allowed more time in the field, we expect a greater proportion of USDA and NY grade tubers and fewer undersized potatoes. 'Vermilion' produced almost no marketable shaped tubers. While 'Luminance' produced more marketable shape and sized potatoes out of the field, the thin, scuffed skin left the variety prone to rot and there was little marketable yield. 'Radiance' did not rot as much as the other stringy tuber-dominated varieties. 'Bonita' produced a large number of on-type, marketable sized sweet potatoes out of the field but losses due to rot were very high after curing and storage. 

The production target for sweet potatoes in warm climates is to 2.0 pounds of marketable yield per plant. The crop is expected to yield less in northern climates. Thus, 1.0 lb/plant is a more reasonable production target for NY. The table below gives the total marketable yield per plant for each of the six trialed varieties. 'Bellevue' reached the production target for NY, despite being harvested a bit early. '18-100' needed more time to size up, as evidenced by the disproportionately high amount of undersized grade potatoes. 'Bonita' would have reached the production target had a large proportion of the tubers not rotted. The other varieties produced too many off-type and damage-prone tubers that subsequently rotted. 

OKRA

The trial experienced losses early in the season due to damping off.  The bare ground plots lost 1-6 (average 3) plants. The row cover only treatment averaged 1 lost plant/plot, black plastic was 0.33 dead plants/plot, and 0 losses occurred in the row cover + plastic plots. Stand counts remained stable from late June until early September, when white mold began killing plants. White mold incidence and severity did not have a relationship to the experimental treatments, it was randomly distributed.  

Crop vigor was measured as height and width of six plants per plot on June 26 (at row cover removal, 3 weeks after transplanting), July 11 (5 weeks after transplanting, just before flowering), and September 5 (two weeks before final harvest). 

Plant width clearly differed between treatments at 3 weeks after transplanting, when the row cover was removed (June 26). The row cover + plastic treatment was 128% wider than the bare ground treatment, measuring an average of 18.3 and 8.0 cm, respectively. The row cover only treatment exceeded the width of the bare ground by 54% while black plastic mulch alone produced a 21% increase in plant width. The row cover + plastic treatment, which warmed both air and soil, produced a greater increase in crop size than the simple sum of the two component treatments. This reinforces that okra is challenged by cool soil and air temperatures around crop establishment and that the combination of row cover and black plastic mulch best loads heat into the soil and retains warmth at night. Less difference was observed in crop height on that date, with row cover + plastic being 28% taller, row cover alone 15%, and plastic mulch the same height as bare ground. Plant width appears to respond well to the use of row cover and the warming of the air around the foliage. Wider plants at 3 weeks after transplanting had appreciably more leaf area and were well-positioned to harvest more light than the bare ground plants. 

Differences in crop size had increased by July 11 (2 weeks later), despite the row cover having been removed. Compared to bare ground plants, plants were 128%, 80%, and 30% wider and 82%, 55%, and 26% taller in the row cover + plastic, row cover only, and plastic mulch only treatments, respectively. The row cover receiving treatments continued to be appreciably wider and taller than the plastic mulch only treatment, even though there was no row cover used between June 26 and July 11. This indicates a lasting benefit and response to the use of row cover at transplanting and suggests that early vigor carries forward into sustained enhanced rates of growth and crop size prior to reproductive development. Plant width was not meaningfully different between the the three season extension techniques by September, when they ranged from 33-42% wider than the bare ground treatment. Plant height continued to be the greatest in the row cover + plastic (41% taller than bare ground), then the row cover alone (25 % taller than bare ground), then plastic alone (16% taller than bare ground. All three season extension techniques produced larger okra plants than bare ground alone from 5 weeks after transplant - end of harvest. Row cover had a larger positive impact on crop size and vigor than black plastic mulch, and the combination of both produced the largest increases. 

EARLINESS
We used short day variety 'Buffalo Bill '91' in this trial. The bare ground treatment averaged 47 days to harvest from transplanting, 9 days earlier than the 56 days typically needed by commonly grown varieties like 'Jambalaya' in our production region. Harvest began at 44.3 days in the row cover only plots and both treatments containing black plastic began producing at just 43 days. Adding row cover to black plastic mulch did not have an advantage over black plastic mulch alone for shortening the time to first harvest. Combining the short day variety 'Buffalo Bill '91' with black plastic mulch resulted in harvesting okra two weeks sooner than is typically achieved using common varieties and bare ground production.

We examined the proportion of total yield that was harvested during the early period.  We defined the early period as anything from the start of harvest until 56 days after transplanting, when most okra produced in the region would be expected to start yielding.  'Buffalo Bill '91' in bare ground produced 9% of its season total yield before 56 days after transplanting. Black plastic mulch alone and row cover alone saw similar increases, respectively giving 13.9% and 15.2% of their annual total yield during the early period. Row cover + plastic mulch produced 24.5% of the total season yield during the early window. 

We are interested in the amount of early yield because growers can often charge a premium for being the first to market. The more of your yield you can sell for a premium before other okra is ready, the more valuable your crop becomes without having to increase yield/plant, plant population, or crop acreage. 

YIELD data was converted to ounces of production per plant to adjust for the variable stand counts. Okra in warmer climates can produce 1-2 lb of fruit per plant. Typical okra yield for many growers in the northeast in an average summer is around 0.5 lb/plant. We experienced a much wetter than typical summer in Albion, NY in 2023 and had a much cooler June than is usual. Our total average yield per plant was 0.43 lb in the row cover + black plastic mulch, 0.39 lb/plant in both the row cover alone and black plastic alone treatments, and 0.26 lb/plant in the bare ground treatment. We realized a 49-66% yield bump by using season extension techniques.  In the cooler spring, wetter summer 2023 growing season, use of season extension techniques allowed the crop to achieve near typical yields and acted as an important economic risk mitigation strategy.

ECONOMICS
A partial budget for the differences between treatments was calculated using trial-experienced input costs and statewide typical marketing prices, as gathered from grower feedback during the trial and in discussion at results presentations. We standardized everything to the costs per 1000 linear feet of production and assumed a single row spaced 18" between plants for a plant population of 667. The black plastic mulch cost $43.50/1000 linear feet.  The row cover cost was $378.00 but because row cover can be reused many times, we assumed three uses and divided that expense by 3, using $126.00 as our cost. There was no drip irrigation used in this study. Therefore, the row cover + plastic treatment cost $169.50, row cover alone $126.00 and the black plastic mulch alone cost $43.50. Though not included in this analysis, a grower could expect a custom tractor rate of $50-75/hour if they choose to hire someone to lay black plastic mulch. 1000 linear feet of plastic can be laid in under 15 minutes with a tractor. 

The row cover + black plastic mulch treatment produced the most yield and the most gross revenue, followed by row cover only and black plastic only with bare ground following by a wide margin. Deducting out the cost of treatment adoption and charging a single price season long, black plastic along becomes slightly better economically than row cover + black plastic while bare ground continues to substantially underperform the season extension treatments by more than $250. The relative economic benefit of the three season extension techniques may shift if row cover is used more than 10 times or if trickle tape is added to the plastic-containing treatments. 

When growers are in markets that reward early crop with a price premium, the greater proportion of early yield produced by the row cover + black plastic treatment led to the combined technique being the best economic performer. Overall, we realized financial improvement of 33-50% by using simple, low-cost season extension techniques! 

Other Observations
Wil reported that his customers responded well to the new variety 'Buffalo Bill '91'. They liked the overall shape, size, and color of the variety and some preferred it to his non-trial planting of 'Jambalaya'.  

Though not included in the formal data collection, we observed that weeding labor was substantially reduced in the black plastic and row cover + black plastic plots compared to the bare ground and row cover alone plots. In this trial, the weeding labor savings associated with plastic mulch use were approximate to be offset by the increased labor needed to irrigate those plots as there was no drip tape used in the plastic-containing treatments. 

Asparagus

Importantly, half of the varieties were 2 year-old crowns established from seedlings ('Guelph Equinox', 'Erasmus', 'Spartacus', 'Grande' and 'Atlas'). These seedling established plants tend to have crowns that are more shallow then the crown-established 3 year-olds ('Guelph Millennium', 'Guelph Eclipse', 'Purple Passion', 'Jersey Knight', and 'Walker Deluxe') despite being planted at the same depth. This means that the 2 year-old age cohort is expected to emerge a little sooner than the deeper 3 year-old cohort. Additionally, the 2 year-olds were only old enough to sustain light cutting while the 3 year-olds were in their first year of production. Because of these differences, all 2023 data can only be compared within age cohorts, except for disease tolerances. Many of the age-related differences will become irrelevant in 2025, when both cohorts will be in their peak productivity years. 

Asparagus emergence can be predicted by growing degree days using 40 ^o F as the base.  Under a model developed by Michigan State, 25% of spears will be up and 1" tall around 150 GDD₄₀.  We tracked GDD₄₀ using the Climate Smart Farming GDD tool, which incorporates weather observations at a 2-kilometer resolution scale. Daily temperatures and precipitation records that were observed at the county airport weather station, located 4.7 miles from the trial site, were downloaded from Wunderground.com.  

Very warm, 70 degree+ late March and early April weather pushed some varieties to emerge too soon. Some crowns had spears cracked through the soil or emerged when herbicide was applied April 8th. The cracking was not visible when the field was scouted two days before herbicide application. The spears exposed during herbicide application exhibited injury symptoms that persisted until they were removed from the plants during the May 1-5 harvests. Spears emerging after herbicide application did not exhibit herbicide injury symptoms. Therefore, the relative amount of herbicide damage within each age cohort also serves as a measure of premature emergence and a lack of frost avoidance traits. The more herbicide injury, the greater number of spears that were emerged or cracking by April 8th.

RELATIVE EMERGENCE BETWEEN VARIETIES
We measured relative emergence between varieties by recording how many plants had spears on May 1, our first harvest date (see % emerged plants 5/1 in data table).  Asparagus in WNY should be up and growing by May 1. Amount of emergence as of 5/1 reveals that nearly all of the seedling-established 2 year-old crown cohort had emerged by May 1st, with little meaningful difference between varieties at that date. The herbicide injury data suggests that 'Spartacus' was the first variety to emerge, followed by warmer climate adapted 'Grande' and 'Atlas'. 'Spartacus' is bred to be an early northern variety that should beat other cultivars to market under normal spring conditions. It appears that the variety is performing as it was intended and is quickly responding to warm soils to provide early yield. Unfortunately, it is not well suited for high-frost risk sites. Its snappy growth at the first warm spell sets it up for trouble in erratic spring conditions. 

The crown-established, 3 year-old cohort broke into three groups. 'Walker Deluxe' was almost completely emerged (99%). 'Millennium', 'Eclipse', and 'Jersey Knight' were 82-88% emerged. 'Purple Passion' was delayed with only 66% of plants emerged by May 1 - a late variety. 

FROST AVOIDANCE
Frost is the more common concern with excessively early emergence. Three reasons why asparagus emerges too soon are erratic warm periods in early spring, shallow crown depths (< 8 inches) and use of more southern adapted varieties. Frost is a compounding economic injury in asparagus. Losing early spears to frost hurts growers in four main ways:

1. Direct loss of marketable yield
2. Delayed emergence of replacement spears. Asparagus will often sit for several days to a week after heavy frost damage before pushing replacement spears. By comparison, the crown quickly replaces harvested spears. 
3. Losing early marketable yield disadvantages growers in the marketplace. Growers may also lose a premium for early production. 
4. Asparagus is a labor intensive crop. Growers may have hired extra labor to pick asparagus, especially on farms with >5 acres. If the crop is not destroyed but only tip-burnt, the damaged spears must be dropped to prevent the crowns from continuing to grow unmarketable spears and hasten development of salable crop. Dropping spears is essentially the same labor investment as a harvest but without any associated income. 

Frost occurred in the trial on 4/25 and 4/27 and damaged spear tips on many varieties. The damage was not so severe as to cause completely collapse, which allowed nearly all frosted spears to be picked for data collection in the May 1-5 harvests. Spears harvested after May 5 no longer had frost damage, meaning they had emerged after 4/27. 

Varieties with more herbicide and frost damage in the May 1-5 harvests were the most quickly developing and would have had the earliest yield (see data table). In the more shallow-crowned 2 year-old cohort 'Spartacus' had the most damaged spears, followed by 'Atlas' and 'Grande'. 'Spartacus' lost 28% of all spears produced in 2023 to early season damage, while 'Atlas' lost 23% and 'Grande' 16% compared to 5% and 2% for 'Equinox' and 'Erasmus'. It makes sense that 'Atlas and 'Grande' are not frost avoidant as they primarily marketed and adapted for warmer climates than NY. 'Guelph Equinox' (green) and 'Erasmus' (purple) had are exhibiting frost avoidance. 

The 3 year-old crown cohort consists of regionally adapted varieties and the crowns are a little deeper than the 2 year-olds. Losses due to early emergence were  comparable to typical losses for western NY. Differences between varieties are much smaller. 'Walker Deluxe' and 'Jersey Knight' lost 7% and 4% of their total spear production to early season damage, 'Guelph Eclipse' lost 1% and 'Guelph Millennium' and 'Purple Passion' lost no spears. All five varieties in the older cohort are regionally adapted.  That said, the 'Millennium' and 'Purple Passion' (purple) did exhibit complete frost avoidance.  The University of Guelph breeding program specifically selected for frost avoidance, so the good performance of their three varieties in this arena is unsurprising. 

These early varieties are the least frost avoidant and are a poor fit for farms with elevated risk of late season frosts. They are also riskier to grow in years with more erratic spring weather conditions. Because the weather is increasingly erratic, average risk farms growing these varieties should expect losses due to frost.  In theory, growers planting new fields might be able to partially mitigate that risk somewhat by planting these varieties at 10-12" instead of 8" to delay emergence but that risk mitigation strategy was not been tested in this variety trial. These early producing, non-frost avoidant varieties might present a market opportunity for farms with low inherent frost risk due to warm microclimates or farms that invest in frost protection measures. For such farms, these otherwise challenging varieties may offer a chance to capture higher price premiums by being early to the market. 'Spartacus' is a variety made for this production niche. 

HARVEST DATA
Among the 3 year-olds, 'Eclipse' produced the greatest number of marketable spears, the greatest marketable weight, and the largest percentage of marketable spears. Individual spears of 'Eclipse' were 22% heavier than spears of 'Millennium', the next best producing green 3 year-old. 'Eclipse' only required 15 spears to make a 1.0 lb market bundle compared to 18-22 spears for the other 3 year old green asparagus. 'Jersey Knight', representative of the old varieties aging out of grower's production fields, produced the fewest number of marketable spears. Only 40% of spears were marketable and spears were light. 'Walker Deluxe' had similar performance to 'Jersey Knight'. 'Purple Passion' produced heavy spears and a high proportion of marketable yield. It's overall marketable yield performance was similar to 'Millennium'. 

The best producing 2 year-old by marketable spear count, marketable weight, and weight per spear was 'Grande'. 'Equinox' produced a better percentage of marketable spears only slightly fewer spears but could not make up for its spears being 35% lighter than 'Grande', which required only 20 spears to make a 1.0 lb market bundle. 'Atlas' required 22 spears, 'Equinox' needed 27, and 'Spartacus' needed 33. 'Spartacus' had a low percentage of marketable spears because many emerged excessively early and were damaged by frost or herbicide. It also produced lightweight spears. Purple variety 'Erasmus' was had the fewest marketable spears and weight of all the 2 year-olds. 'Erasmus' did not suffer early losses and had the least amount of over mature spears. Evidence suggests 'Erasmus' has fewer below ground resources and production capacity at this young age than the other four varieties in this cohort.  

Over maturity: Many of the over mature spears occurred on May 12 and May 15.  This is largely a function of our harvest schedule. We elected to wait an extra day between May 9 (Tuesday) and May 12 (Friday) during the warm weather to challenge the varieties and see how the tips held under heat and fast growth conditions.  A number of otherwise marketable spears became over mature because of the longer gap between harvests. We learned that 'Purple Passion' holds its tips well and continues to develop at a steady pace. extended harvest window does happen on commercial farms, too. 'Walker Deluxe' grew quickly and was fast to start opening up the bracts. While 'Millennium' produced more pounds of over mature asparagus than 'Walker Deluxe' even though it had fewer spears because each Millennium spear produced weighed, on average, twice as much.  Among the 2 year-old cohort, 'Equinox' was more prone to over maturity by both spear count and weight than the other varieties while 'Erasmus and 'Atlas' were least troubled by over maturity. Because our purposeful harvest delay sent the crop went over mature, we summed both marketable and over mature yield for the season it would have been salable had we stuck to timely harvests. 

Undersized production: Undersized spears are produced occasionally amidst marketable sized crop during harvest. We found that 'Millennium' and 'Purple Passion' produced the fewest and 'Walker Deluxe' produced the most undersized spears in the 3 year-old cohort. There were more undersized spears in the 2 year-old cohort which is consistent with being younger. 'Equinox' had the most undersized spears than while 'Erasmus' and 'Atlas' had the fewest.  

Mechanical culls: Mechanical damage is mostly caused by difficulty cracking through crusty soil, large rocks, stem abrasions caused by sand blasting or insect feeding, and nicks inflicted while harvesting other spears. For the most part, these are random injuries that did not amount to more 1 - 3 spears per 25 row feet (plot). However, 'Eclipse' and 'Purple Passion' had higher mechanical damage incidence than other varieties. This trend also occurred in 2024. Observations indicate that 'Purple Passion' is more prone to twists or curls during emerging if the soil is crusty or if it encounters rocks.  The larger spears are more effected than smaller diameter spears. While the reason for elevated mechanical damage in 'Eclipse' is unclear, it also produces large diameter spears than most varieties. Damage in 'Eclipse' tended to be less pronounced than in 'Purple Passion'. 

LENGTH OF HARVEST WINDOW
Harvest started on May 1. All varieties produced at least one spear per plot by May 1 except 'Purple Passion' and 'Millennium', which began May 3rd. Harvest stopped on a plot once the majority of crowns were no longer producing marketable spears. The final harvest for 'Erasmus' and 'Spartacus' was May 17th. These two Bejo varieties were raised from seedlings. They may need longer than the other seedling varieties to develop the crown strength and therefore had a shorter cutting window in their light cut 2 year-old crown year.  'Atlas' finished on May 19th. This variety struggled as a 1st year crown and finished the 2022 season with smaller ferns than the other seedlings. Combined with the heavy damage taken in the spring, it makes sense that this variety ran out of gas before the more regionally adapted 'Equinox' and 'Grande', which finished cutting on May 23rd. The 3 year-old, full production crown varieties 'Walker Deluxe' and 'Jersey Knight' also received their last cut on May 23rd. The three frost avoidant varieties 'Purple Passion', 'Eclipse', and 'Millennium' were still producing a handful each of marketable sized spears at a steady pace each harvest (4, 6.25, and 2.75 per plot, respectively) when we ended our cutting season on May 30th, 2023. This indicates that in 2023 the frost avoidant 3 year-old crown varieties occupied a later production window overall, rather than a steeper concentration of their yield during peak cutting. Indeed, this is easily visualized by looking at the number of total spears harvested (all grades) per harvest date (see line charts below).

RATE OF SPEAR DEVELOPMENT
We used the total number of spears per harvest as a proxy for rate of spear development. Because we cut every spear once it reached 12" tall and left no oversized spears for the plants to invest energy into, all growth was consistently focused into new spears until harvest ended. Therefore, the more spears harvested per day, the faster the crop was growing. 

Varieties with few spears harvested on May 1 are exhibiting resistance to emergence under unusually warm spring weather conditions, or frost avoidance. Those varieties are the three Guelph varieties 'Millennium', 'Eclipse' and 'Equinox' and the two purple varieties 'Erasmus' and 'Purple Passion'. Cool temperatures from May 1 to May 5 caused a slight drop in harvest on May 5 and allowed us to delay our next harvest until May 9th without allowing the crop to become over mature. Temperatures spiked into the 70s and 80s from May 9-13. This corresponded with when the asparagus was gearing up for peak production and pushed the crop to make a concentrated spike in production on May 12. Aside from a snap cold day on May 17 that brought a touch of frost May 18th, daily highs were mid-60s to mid-70s through May 23. These conditions promoted continued growth and quick recovery from the cold night as the crop finished its 2023 production cycle. 

The seedling-established 2 year-old varieties quickly tapered off quickly after the production peak, having put out the majority of their yield over a one week period. We stopped cutting the all of the young varieties within 2-8 days of May 15th. 'Erasmus' produced fewer spears than others in its cohort and was tied for first to stop producing, despite starting slower than all cohort varieties except 'Equinox'.  This indicates that 'Erasmus' is both somewhat frost avoidant and had less crown and energy reserves than the other 2 year old varieties. It may need more time to develop crown strength or be struggling more than the others with the heavier-than-normal gravel silt loam soils (asparagus prefers lighter ground). 'Guelph Equinox' did not push out quite as many spears during the peak as 'Atlas', 'Grande' and 'Spartacus'. It instead had a lower and longer lipped bell shaped production window that was shifted later in the season, indicating frost avoidance and capacity to produce later in the year. 'Grande' also showed capacity to produce later in the year and was not seemingly held back by having sent up spears too early, as 'Spartacus' and 'Atlas' were.  

The 3 year-old crowns followed a similar pace of development pattern. 'Walker Deluxe' and 'Eclipse' responded more strongly to the warm temperatures and produced more spears during the peak than 'Jersey Knight', which produced more than 'Millennium'. The percentage of season-total spears produced during the week of peak production (May 9-May 15) was 77% for 'Walker Deluxe', 75% for 'Jersey Knight', 70% for 'Millennium' and 'Eclipse', and 62% for 'Purple Passion'. Indeed, 'Purple Passion' had a much flatter production pattern. This is partially a function of it being less responsive to the heat peak and also partially a function of the spear characteristics. 'Purple Passion' produces very heavy, large spears and, based on observations only, seems to invest in only 1-3 spears at a time while the other varieties may have 3-5 or more spears above ground in peak production. 'Walker Deluxe' and 'Jersey Knight', the two varieties that started sooner, tapered out quickly after May 19. 'Purple Passion', 'Millennium' and 'Eclipse' continued a light harvest from May 19 through May 30. 

RATE OF SPEAR DEVELOPMENT COMPARED TO TOTAL SPEAR PRODUCTION
Looking only at the rate of spear production obscures the total spear production of the varieties. It would be easy to confuse varieties with the strongest peak response for those with the greatest number of spears produces. The stacked bar charts below help visualize both elements at once. You can immediately see that 'Eclipse' and 'Walker Deluxe' produced more spears than the other 3 year old crowns. This representation helps clarify that 'Millennium' and 'Jersey Knight' are similar producing a similar number of spears and that these two varieties are not producing drastically more spears than 'Purple Passion'. Varieties with more black and red at the base produced a greater proportion of their total spears early in the year while those with more brown at the top continued producing spears until the end of May. 

Overall, the younger 2 year-old crowns did not produce as many total spears as the better resourced 3 year-old crowns, as expected. The shorter production season evidenced by the lack of brown and, on most varieties, purple bands is also consistent with younger plants having fewer carbohydrate reserves and crown buds to support extended harvesting.  There noticeable differences in the black bands amongst the 2 year-old cohort clearly illustrates their divergent responses to excessively early spring heat. This age cohort started producing sooner in the spring than the 3 year-old cohort because the 2 year-old, seedling established group developed crowns that sit slightly more shallowly than depth of the 3 year-olds. Finally, you can see that 'Erasmus' is falling behind the other 2 year-olds in terms of total spear production, suggesting it did not have as many crown resources to draw upon. 

Just as the rate of spear development does not easily portray the total number of spears produced, the number of spears produced does not necessarily relate well to the the number of marketable spears or marketable weight of asparagus produced. For example, while 'Spartacus' produced the most total spears of all 2 year-olds, it produced the second fewest marketable spears. 'Equinox' produced more marketable spears than 'Atlas' even though 'Atlas' grew more spears overall. 'Atlas' and 'Spartacus' both lost a lot of spears to frost damage. In the 3 year-olds 'Walker Deluxe' made the 2nd most spears but was only 4 out of 5 for the number of marketable production. This is because of two compounding factors: so much of its production (77%) was concentrated during the heat (strong spike in rate of development) and difficulty holding tips in hot weather (38% of all spears were over mature). Although 'Millennium' produced fewer total spears, it had higher marketability because it held tips slightly better (31% over maturity) and only 70% of its production was concentrated in the peak. Furthermore, Millennium's frost avoidance shifts it into a later production window and allowed it completely escape early season damage.  'Walker Deluxe' lost 7% of its produced spears to frost and herbicide. Deciding which asparagus variety is best performing and teasing out why requires careful examination of all factors and their interplay. 

DISEASE TOLERANCE & OTHER SUMMER STRESSORS
Disease was the only summer stressor of note. Rust was first noted in 2023 on May 23. Rust was present in 2022 and untreated, so there was plenty of inoculum to ensure even exposure and good pressure across the trial. Rust tolerance can be compared across all varieties because that trait is genetically derived and not influenced by age. 'Rust was observed on susceptible varieties Millennium', 'Eclipse' and 'Jersey Knight'  but not susceptible 'Purple Passion'. Rust was not consistently observed on any of the other varieties. Rust tolerance is a known weakness of the older Guelph varieties, as experienced in this trial.  Time will tell if their new release 'Equinox' has improved rust performance. Our observations in 2023 did suggest that 'Equinox' is less susceptible than 'Millennium' and 'Eclipse'. No other diseases were observed. The trial was treated for rust in mid-July because it was serving as a continuing inoculum source for the rest of the grower's field. Little pressure was seen after treatment. 

Of note, the hot climate adapted variety 'Atlas' was selected for inclusion in this trial because it has strong tolerances to a number of diseases, including rust and cercospora. Cercospora is an emerging disease in the Northeast, previously thought not to be a problem north of Maryland. There have been a handful cases in western NY since 2018. Cercospora is expected to become more problematic as our summers become hotter and wetter. WNY is on the edge of 'Atlas' productive range but it is being trialed because no northern adapted varieties offer cercospora tolerance. Readers in the southern portion of NESARE's region may benefit from exploring 'Atlas' as a variety for heading off disease issues.