Final Report for FNE01-384
Note to readers, attached is the complete final report for FNE01-384
The purpose of this project was to determine if an apple orchard management plan that used EPA “reduced risk” pesticides and approved organic pesticides in an integrated pest management (IPM) program for insect and disease control could produce quality fruit. Lou compared this “reduced risk” program to a baseline IPM program developed on his farm in 1998 and to a certified organic control program.
The trials in the three orchards did not produce dramatic differences in fruit quality, but did produce some notable differences. Lou indicates that the growing season had light pressure from both insects and diseases and believes that if the insect and disease pressure had been higher, the differences from the three orchards may have been more dramatic, particularly from disease damage
Even though it was difficult to discern performance differences between the three management plans, Lou is making changes in his orchard management plan as a result of his study. He is discontinuing the use of one fungicide in favor of a program with two or three other fungicides that he believes are safer. He is changing his management plan for European sawfly to cut down on damage that has been increasing over time. And he is changing his insecticide choice for codling moth and oblique-banded leafroller to reduce potential health hazards from his previous choice of materials.
The farmer reports:
The trial was somewhat inconclusive due to the favorable natural conditions for apples in our area during the summer of 2001. Under more difficult conditions with a warmer spring and more rain, I believe the differences in the three orchards would have been more dramatic. The trial and concurrent study on new (and old) pesticides and fungicides did help us plan our orchard management plan for 2002. Some of the changes we will make in crop protection are:
1. We will discontinue the use of NOVA as a fungicide. The unanswered health aspects of NOVA and the existence of the new reduced risk fungicide FLINT are the reasons. FLINT works at least as well, and I believe is safer. We will use either Sulfur as a contact fungicide and/or perhaps Vanguard early in the season and just prior to bloom. Hopefully we can avoid resistance build up with this scheme and minimal sprays. In the organic orchard we will continue to use Sulfur.
2. We will use Sulfur and /or Avaunt prior to bloom to try to cut down damage from European Sawfly, which continues to be on the rise.
3. We will discontinue the use of IMIDAN, for reasons of new health hazards uncovered during the EPA’s Food Quality Protection Act analysis and review. We will use Avaunt for PC if approved in New York in March as expected, and will continue to use Dipel DF for CM and OBLR. If Avaunt is not approved we will use Surround for PC in spite of the application, picking and cleaning nuisance it involves.
I believe this trial and update on pest management materials has been helpful in formulating our future apple pest management plans. I continue to believe that the health of the trees and the orchard (and farm) environment resulting from organic practices is an extremely important aspect of growing apples, and that no insecticide or fungicide application scheme can make up for poor or unsustainable practices. I hope this study will be helpful to other apple growers. We will take every opportunity to pass on this information to other growers, as we have in other Elderberry Pond SARE Grower Grant Programs.
The purpose of this project was to determine if an apple orchard management plan that used the new EPA “reduced risk” sprays along with approved organic sprays could produce quality fruit. The intent was to compare fruit produced this way to fruit produced in the same year using our standard IPM spray program, which was outlined in the final report of SARE project 98-233 prepared in January of 1998. In this 1998 program the fungicide NOVA was used for disease control and the organophosphate Imidan for insect control. At the beginning of the program we decided to add an additional comparative orchard to the trial using only NOFA Certified Organically approved techniques and sprays to control insects and disease. As it turns out this additional trial was valuable in interpreting the results from the other trials.
We believe that it is important to decide early on what qualities you consider important in your apple crop, as this has a large impact on what disease and insect control measures you will undertake. There is a very direct link between production cost, farm worker and consumer safety, environmental impact and final fruit appearance. I believe this link exists whether you are growing organically, using conventional timed sprays or using reduced spray IPM practices. At Elderberry Pond our goals are as follows:
1. Achieve a ratio of 70% fruit that is good enough to sell at markets where the customer selects their own apples from large baskets. The other 30% go to value added products such as jelly, breads, pies and cider. We have found that “good enough to sell from a selection basket” means nearly perfect in our markets. A single very small PC scar, or Scab mark will not deter selection, but any indication of worm damage or a larger Sawfly scar will.
2. Guarantee our customers that there are no harmful residues of pesticides or fungicides on the apples they buy or in our value added apple products. We do this by using no sprays within 1 month of harvest, by using only sprays that have rapid breakdown, and by brush washing ALL apples that are sold or used in products.
3. Insure that our apple orchards are safe to walk or work in, and that the water run-off from these orchards into our ponds and streams is safe. This means using as few spray trips through the orchard as possible, using sprays that have relatively low toxicity, short toxic lifetimes, and little chance of run-off.
The biggest problem in achieving these objectives has been in understanding the risks of the spray materials we use. The information on pesticide dangers is conflicting and changes each year. This past year new information Imidan and on Rotenone that link these materials to specific human disorders make the future use of these two products on our farm unlikely. Fortunately each year new products with more selective toxicities are registered, and many of these products are believed to have much lower mammalian toxicity. The challenge is to continually push to achieve our fruit quality standards with lower and lower toxicity sprays. That is why we have conducted these trials, and have continued to change our baseline orchard management program.
The 2001 Apple Growing Season
The growing season was, like most, good and bad. It was one of the cooler springs, as can be seen in the degree-day chart in Figure 1. In spite of the cooler than usual spring there were no late frosts or other harmful weather events, and pollination was excellent. Disease pressure was extremely light, with only one primary scab infection period in early May, based on leaf wetness time and temperature, and this period was marginal for a strong primary infection event. It was the driest April in recent history in our area, but despite this it was our most productive apple-growing season ever. The photos below show some of the excellent crop near harvest time.
Insect pressure was later and lighter than usual, perhaps to the delay in spring warming. Plum Curculio, for example normally is spotted in our traps in the plum orchard in early May with first visible scars in mid May. This year PC appeared in the Plum Orchard traps around May 17th and first scars in the Smokehouse apples (their favorite) did not appear until mid June! Apple Maggots appeared in early July, on schedule, but in very small numbers, with about 10% of normal catches throughout the season.
The apple season was a bit cool, very dry, but long with our earliest pickings of Pristine in the first week in August and the final picking of Goldrush, and Fuji during the last week in November. The yield was our best ever, and the overall quality from all three trial orchards very good to excellent. As a side note, our best selling varieties were similar to previous years and were in order of demand: Honeycrisp, Spitzenberg, Pink Pearl, Goldrush, Dayton, Enterprise, Gala, Empire and on from there.
The trials in the three orchards did not produce dramatic differences in quality of fruit, but did produce some notable differences. Had this been a more difficult year with more disease and insect pressure, the differences in the results from the three orchards might have been more dramatic, particularly in disease damage. In the remainder of this report the control strategies in each orchard will be discussed with respect to the most significant disease and insect problems. A summary of the quality of fruit produced in each orchard will then be presented.
4. Apple Scab Control in the Three Orchards.
Baseline 1998 IPM Orchard
In this orchard I tried to stick with the practice that we have been using since our SARE trial in 1998. Some light dormant pruning was done in early April. On April 23rd, just as some of the trees were beginning to show green on the tips, we applied the first spray of dormant oil and the fungicide NOVA. The NOVA was applied as a preventative spray, as some significant amount of rain was expected. The temperature had been cool, 50’s during the days and 30’s at night, and no significant warming was predicted. As it turned out very little rain fell, and the temperatures remained too low for a primary scab infection. This was sort of the story all during the spring scab infection period, cool and very little rain, with no extended periods of leaf wetness. One additional NOVA spray was applied in early May, again just before a predicted rainfall, but very little rain fell, and I doubt there was a serious release of scab spores. No additional fungicide sprays were applied during the season, and as will be shown later there was very little scab evident on leaf or fruit at harvest.
Lower Risk IPM Orchard
In this orchard the spray FLINT was used on exactly the same schedule as in the conventional orchard. The results were about the same as in that orchard, though even less evidence of scab on leaf or fruit was evident at harvest.
Certified Organic Orchard
In this orchard early oil spray was applied and the first fungicide spray (Sulfur) was applied just before the light rain in May. It was slightly sooner than the recommended 30 day period advised between oil and sulfur, but no obvious damage was done. This was the only fungicide spray applied during the year. There were some small scab spots on about 20% of the apples, but not enough to have warranted any additional sprays.
This was a very unusual spring with record low rain and record low temperatures, so it is difficult to reach any meaningful conclusions. It does clearly show the value in watching the weather, particularly leaf wetness and temperature. It also shows the value of using the newer fungicides that have long (up to 96 hour) reach-back. It would have been possible in this particular spring to use no Fungicides if you were willing to rely on the reach back capability of FLINT. Using contact fungicides such as sulfur, requires that you spray before, during or perhaps right after the infection for good control. In the organic orchard we took lots of risk by holding off sprays during several periods where rain was predicted. It worked out this year due to low temperatures, but I would guess most organic growers would have sprayed sulfur three of four times (as I would have had the organic orchard been my only orchard.)
Scab Control Strategy For 2002
Our scab control strategy in our 2002 baseline orchard based on this trial, data from our 2000 orchards, and on the toxicity information contained in table 2, is as follows:
Early sprays at tight cluster and pink will be with FLINT, the new strobilurin class fungicide used in our trials this year. The reach-back characteristics (96 hours or more) make it possible to time the sprays and perhaps to avoid a spray altogether if a suspected infection period doesn’t materialize. From a safety and environmental protection point of view it appears to be the best of all currently approved choices, including those approved for organic production.
At or near petal fall we will use a contact fungicide such as sulfur or perhaps Cyprodinil (VANGUARD or SWITCH) if they are approved. This year the stretch between pink and petal fall was long and with little previous rain to decrease the supply of ascospores, it appeared to be a high-risk of infection period. The sprays during late bloom seemed to work well including the sulfur spray on the organic orchard. Another possible reason to use sulfur during the late bloom period is that the organic orchard showed much lower incidence of European Sawfly Damage. I think it may be that the presence of sulfur at the base of the stamens deterred or killed the Sawflys or larvae and decreased the damage. The difference in the two orchards was dramatic.
Following petal fall, if the weather dictates, we will use FLINT through first cover. FLINT offers fairly good protection from Powdery Mildew. In this past year we had some serious PM on our Liberty Trees. We never spray these with any fungicide. This year was the first
year we have had an outbreak. It nearly defoliated two or three trees and damaged the foliage on several others. The mild winter (lowest temp –3deg F.) and long dry spring was favorable to the development of PM. The bordering trees that were sprayed with FLINT and are PM susceptible varieties (Empire), showed no sign of the disease. In the future we will include the Liberty (known to be susceptible to PM) in our post bloom sprays.
In my opinion the risk in the above program is not high from either safety or a fruit quality points of view. The program could, however, lead to the selection of strobilurin resistant strains of scab. My hope is that with the contact fungicide substitution at early petal fall, and perhaps once before petal fall, and with only two or at most three, applications of FLINT we will be OK. I have read of no scab resistance to strobilurins, but the chemistry is new and the manufacturer warns of the possibility. It is interesting to note that the fungicide SOVRAN, which like FLINT is a Strobilum Class fungicide derived from the fungus Strobilurus tenacellusis is often listed as an equivalent substitute to FLINT having similar, if not better, scab and PM knockdown characteristics. The chemistries are however different and in fact
the active ingredient in SOVRAN, Kresoxim-Methyl has been determined by EPA to be a likely Carcinogen 2.
6. Plum Curculio and European Apple Sawfly
Plum Curculio and European Apple Sawfly were the pests that resulted in the highest number of apple blemishes in this trial.
Baseline 1998 IPM Orchard
In this orchard we used Imidan to prevent Plum Curculio damage. To determine when to spray we used the two-piece triangular black ground traps baited with apple essence. The traps were placed in the plum orchard located between the Organic and Conventional IPM orchards and in the Conventional IPM Orchard. The first trap catches were in mid May, and the first Imidan application was on May 22. Trap catches continued well into June, and a second Imidan spray was made on June 17th. This spray was slightly over 340 degree days after petal fall, when the NYSAES, Geneva model predicts oviposition to be over 40% complete, and further spraying for PC not necessary, and was primarily made for first flight codling moth. In retrospect this spray may not have been necessary, as there were no, or very few PC scars on the apples in this orchard. No more Imidan Sprays were applied to the orchard and damage from PC was minimal (3%).
As for European Apple Sawfly no traps were used and no sprays were applied prior to petal fall. This pest has been present in our orchards for three years and each year more damaged fruit is observed. The adults begin to emerge from the soil at pink, and females begin to lay eggs during bloom. The larvae tunnel, creating a large circular scar at the calyx end of the apple. In this orchard as much as 17% of the fruit showed some sign of EAS scars. Later in the season the larvae may emerge from the scarred fruit and enter another fruit causing damage similar to Codling Moth. We did not see evidence of this damage in our fruit, perhaps due to the June application of Imidan.
Lower Risk IPM Orchard
In this Orchard we had planned to use Avaunt to protect against both Sawfly and Plum Curculio, but could not get the product due to the lack of general registration in New York. We decided to use Surround, but felt we could not use it during bloom, which for our orchards with over 100 varieties of apples extends for about three weeks. We applied the first spray of surround of 5/20. We felt we got good coverage with our hand wand, but it was not pleasant work. We used surround at the 50 Pound per acre rate, and with 25 pounds per 50 gallons water. Because of its bright white residue, it makes you appreciate how much of whatever you’re spraying with gets on your tractor, sprayer, clothing, etc. Within a few days after spraying we began to notice scars on the small apples, both PC and sawfly. (See photos below) The surround lasted quite well in the trees due in part to the lack of any heavy or long lasting rain. We sprayed again in early June, since we were seeing scars, in many cases right through a heavy layer of the clay (see photo below). I’m not sure why, perhaps due to insufficient coverage, but the damage from sawfly was nearly 20% and damage from PC was about 15% in all varieties in this orchard.