Apple Replant Disease – Theory Versus Practice, an Overview of Known Controlling Methods

Apple Replant Disease – Theory versus practice, an overview of known controlling methods

By H. Meints & A. Toma

Summary

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma Contents 1. Background of apple replant disease (ARD) ...... 2 2. Control methods applied for ARD ...... 2 2.2 Swapping the soil ...... 2 2.3 Using compost and compost tea ...... 2 2.4 Using resistant strains ...... 3 2.5 Testing the soil ...... 3 2.6 Removing old plant matter ...... 4 2.7 Growing ‘Break Crops’ ...... 4 2.8 Fumigating the soil ...... 4 2.9 Alternative methods on fighting ARD ...... 4 2.10 Anaerobic Soil Disinfestation ...... 4 3. Experiments and their outcomes ...... 5 3.1 A closer look over microbial community development ...... 7 3.2 Wheat - the chief mediator ...... 8 3.2 Brassica seed meal amendments as alternative to soil fumigation...... 8 3.3 Herbie – an efficient fighter against soil borne pathogens...... 9 4. Conclusion and recommendations ...... 12 5 Field trials photos ...... 13 6. Annex 1 ...... 16 7.References ...... 22

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

“Innovation is not just technology, but is rather a comprehensive vision of what the future should look like and which requires changes in many ambits. Innovation is driven by people’s needs, ambitions and dreams, and requires that people at different positions in society change the way they work and live.” (Klerkx et al, 2012)

1. Background of apple replant disease (ARD)

Replant disease is a debilitating soil problem affecting most orchards when they are replanted. Symptoms normally affect the entire orchard and include slow, uneven growth and poor tree performance. Due to the general nature of replant disease, it is easy to be unaware that it is present, or to blame the rootstock or nursery for poor tree performance. Replant disease affects most fruit crops including both Pome and Stone fruit (Brown,2013). During the life of an orchard, soil-borne pathogens belonging to the genera Rhizoctonia, Pythium, Phytophthora, Cylindrocarpon and Pratylenchus become prevalent in the tree root zone, but they generally do not appreciably affect the health or productivity of mature trees (Mazzola, 1998; Mazzola, 1999). To this date, previous studies categorized replant disease as having two forms - specific and non-specific. It is assumed that specific apple replant disease only affects apples when they are planted after apples, while non-specific replant disease affects apples that are replacing other fruit crops, such as stone fruit or vice versa (Brown,2013). The severity of replant effects can vary from site to site (Hoestra, 1968; Mazzola, 1998). The symptoms mentioned above include reduction in tree vigor and yield (Traquiar, 1984), and the fact that affected trees start bearing fruit 2–3 years later than unaffected trees. According to Mazzola (2004;2009;2015), in apple replant disease, an important aspect to be taken into account is the microorganisms variety built-up in the root zone of the trees, while applying prevention and control strategies.

2. Control methods applied for ARD

When it comes to prevention methods and treatments of ARD, opinions vary, as it is a complex disease involving different causal factors. However, we will briefly list the most common measures found in the literature and further discuss some of them more in depth in the latter part of the article.

2.2 Swapping the soil

When is needed to replant apple trees in the same location – or if planting in a new location isn’t viable – then soil replacement can be an effective method for smaller sites. It’s important to ensure that high quality soil will be used and moreover, it doesn’t come from any fruit tree planting source. Specialists recommend that the replacing soil should be spread on an area larger than the tree’s roots coverage, while any old soil will be disposed.

2.3 Using compost and compost tea

St. Martin and Brathwaite (2012), define composting as “the controlled, microbial aerobic decomposition and stabilization of organic substrates, under conditions that allow the generation of Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma high temperatures by thermophilic microbes, to obtain an end product that is stable and free of pathogens and viable weed seeds and can be used in plant culture. The end product, which is a solid particulate extracted during the maturation and curing phase, is termed compost (Litterick and Wood 2009)”. Further, compost tea can be referred as “filtered products of compost brewed in water (Litterick et al. 2004) and brewing, a steeping process of compost in any solvent (usually water), which lasts for more than one hour “(NOSB 2004). As many previous studies show, soils amended with compost can partly or wholly suppress soil borne phytopathogens and plant diseases (Dickerson 1999; Fuchs 2002; Tilston et al. 2005). Hoitink et al. (1997) argues about “two classes of biological control mechanisms known as "general" and "specific" suppression that have been described for compost-amended substrates. The mechanisms involved are based on competition, antibiosis, hyper parasitism and the induction of systemic acquired resistance in the host plant”. The use of compost as an alternative to fumigation, has gained the attention of both farmers and scientists alike. However, the limited knowledge over the influence of compost usage on the soil biological communities and microbial and metabolic dynamics, doesn’t confer this practice full trust among farmers. When it comes to disease suppressiveness , St. Martin(2015) argues that a higher level was observed where compost mixes were applied before every two croppings compared to those applied only at planting. Moreover, referring to the absence or presence of residual, cumulative or delayed suppressive effects, most studies show that where >50 % disease control was recorded, compost was applied at a rate of at least 100 tons/ha (Coventry et al. 2006; Zaccardelli et al. 2011). The application of such high rates, exceeds the established limit of 30 tons/ha for green composts and 20–30 tons of green or food- derived compost/ ha set for nitrate vulnerable zones (NVZs) (Council Directive 91/676/EEC 1991). Furthermore, these rates can become potentially hazardous to the environment, especially in relation to groundwater and surface water pollution and the conveyance of heavy metals to the soil. Another limitation in using compost as disease suppression method, is the possibility to replicate and standardize the compost quality across production batches and differences in climate, soil type, crop production practices and/or experimental protocols used in the field. (St. Martin,2015). Till today, this has been one of the important impediments in making compost a recommended method against diseases when it comes to commercial crop production (St. Martin,2015). As Stone et al. (2004) suggests,” inducing general or specific suppression in soils using compost or compost tea might not be sufficient or possible to achieve commercially viable disease control in many disease and cropping systems. In such cases, other strategies or combinations of strategies such as the use of crop rotation, cover and rotation crops, tillage and inputs including plant genetic resources and amendments will be necessary”.

2.4 Using resistant strains

It is known that many strains of fruit trees like M27 apples, ‘Colt’ cherries or Myrobalan B plums are more resistant to replant disease than others.

2.5 Testing the soil

Soil tests could provide vital information on Ph levels, soil fertility and microbial communities. It is recommended that the soil testing and analysis be carried out a year before planting. This will allow the grower sufficient time to determine fertilizer requirements as well as whether any specific adjustments are required to the soil Ph levels. At the same time, an overview of the soil-borne pathogens present in the tested area would give valuable insights on grower’s future decisions. Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

2.6 Removing old plant matter

It is advised to ensure the removal of old plant material as soon – and as thoroughly – as possible, while taking special care to remove all traces of roots during this process.

2.7 Growing ‘Break Crops’

When possible, avoiding replanting similar species in the same spot might be helpful. For many, this may not be practical, but growing a ‘break crop’ can often play a vital role in prevention, as Stelljes (2000) argues. Following the ‘Pomes and Stones’ rule can also prove effective, meaning that instead of following a ‘Pome’ fruit with a fruit from the same group, a ‘Stone’ fruit should be a good replacement crop. This method is not guaranteed, as these trees can still be susceptible to non-specific replant disease (which affects Pomes trees that are planted after Stone crops, and vice-versa).

2.8 Fumigating the soil

Apparently, soil fumigation leads the fight against ARD, with several treatment options available on the market, depending on the crop in question. Methyl Bromide was once commonly used to control apple replant disease in the 90’s, but has since been phased out for years now (due to environmental concerns), leaving the role to other alternative products such as Chloropicrin, the most used one. This specific fumigant proved to be effective combatant in the war against ARD as studies shown (Line,2005). But pre-plant fumigation has also its disadvantages as it negatively impacts on the health and diversity of soil biological communities (Hoagland et al,2012). Another example of “two faced” product is metam- sodium, a fumigant commonly used also to treat apple replant disease, which has been found to disrupt beneficial free-living nematodes, mycorrhizae, and beneficial bacteria and fungi that cycle nitrogen (Cox, 2006). Additionally, this chemical is a carcinogen that can negatively impact farm worker health (Cox, 2006).

2.9 Alternative methods on fighting ARD

The need to find effective strategies in combating apple replant disease emerged over years, as continuum research takes place. Through the lab and field trials, different lessons have been learnt in time and related reports were published to share the knowledge. For instance, methods like digging holes and filling them with imported soil that is free of the causal pathogens is not cost-effective in a large orchard, and proved to only control disease symptoms for the first year or two (Anonymous, 2001). At the same time, leaving soil fallow for an extended period of time has also been ineffective in controlling the causal pathogen complex (Mazzola and Mullinix, 2005; Fuller, personnel communication).

2.10 Anaerobic Soil Disinfestation

Anaerobic soil disinfestation (ASD) which may also be known as ‘biological soil disinfestation’ or ‘reductive soil disinfestation’ represents a pre-plant (non-chemical) soil disinfestation technique and is more often proposed as an alternative to chemical soil fumigation (CSF) when it comes to controlling several soil-borne diseases, plant-parasitic nematodes, and weeds in different vegetables and fruit crops (Shennan et al. 2014; Rosskopf et al. 2015). Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

After being developed independently in Japan (Momma et al., 2013) and The Netherlands (Blok et al., 2000), for both open field and protected crops, ASD has gained interest all over the world (Shennan et al., 2014).

1Number of studies by country and USA states and response variables examined. Shrestha et al (2016)

“The principle of the technique is to create a temporary anaerobic soil environment to stimulates the growth of facultative and obligate anaerobic microorganisms, that under anaerobic conditions, decompose the available carbon (C) source, producing organic acids, aldehydes, alcohols, ammonia, metal ions, and volatile organic compounds, that are suppressive or toxic for several soil-borne pests and diseases “(Momma 2008; Huang et al. 2015; van Agtmaal et al. 2015).

In the scientific literature, ASD is described as having three stages: 1) amending the soil with a readily decomposable C source to initiate rapid soil microbial growth and respiration, 2) covering the bed with oxygen impermeable polyethylene mulch to prevent the diffusion of oxygen from the soil surface, 3) irrigating the soil to saturate the pore space and further reduce the presence of oxygen (Butler et al., 2014; Shennan et al., 2014).

3. Experiments and their outcomes

In the past decades, many scientists conducted laboratory and field trials, experimenting ways to prevent and control ARD. From testing the efficiency of chemical products to exploring eco-friendly alternatives, all those initiatives came to their very own conclusions. In Shrestha et al (2016), an in-depth analysis was conducted, reviewing a consistent number of publications related to ASD. Their work suggests that anaerobic soil disinfestation “can work as a replacement to chemical fumigants for pathogen suppression as we observed consistent pathogen suppression under various conditions”. They also identified that ASD treatments proved to be more effective under higher soil temperature for both nurseries and field conditions. For example, having a soil temperature above16°C can influence the incubation period, which can be reduced to less than 3 weeks. However, under temperature below 16°C, ASD can be effective under modification of certain factors, as in the example they mentioned - Ralstonia and Verticillium were effectively suppressed when higher amendment rates (grass) and longer incubation periods of 10 to 25 weeks were practiced (Shrestha et al, 2016). Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Another aspect to be considered is the difference between the levels of pathogens suppression level conducted in as potting soil or other laboratory media and results obtained under field conditions. In Shrestha et al (2016) it is mentioned that “among various types of soil, clay and sandy soils showed low suppression of pathogens in response to ASD treatment. Reasons for this observation may include low availability of C to microorganisms due to rapid loss of soluble C in sandy soil and greater adsorption and reduced water infiltration rate that affects the distribution of decomposition by-products in clay soils. Clay soils are also likely to be more buffered against changes in soil pH that may affect the accumulation of VFAs. Further, these acids are weakly adsorbed to the soil’s exchange phase and have rapid turnover 2 Comparisons among levels of (A) crop type, (B) study type, (C) soil type, (D) soil rate with short half-life (Jones et al., 2003) temperature, and (E) incubation period; Number of studies reporting data for and transitory when exposed from each level of moderator is given in parentheses (Shrestha et al,2016). anaerobic to aerobic condition (Lazarovits et al., 2005). Whereas volcanic ash, loam and gray lowland soil showed more suppression than clay and sand as these soils are themselves more fertile with high mineral contents which often enhance microbial activity”.

Experiments showed that a major benefit of ASD is that it can control pathogens under relatively short incubation periods: for an incubation period <3 weeks - 77% pathogen 3 Comparisons among levels of (A) forms, (B) mixed, (C) types, (D) unamended and (E) Rate per m2. Number of studies reporting data for each level of moderator is given in parentheses (Shrestha et al,2016) control, depending on study type and soil type. As previous studies argue, incubation periods below3 weeks were reported from small-scale studies, including lab studies and only few large-scale studies, which included volcanic ash and gray lowland studies (Shrestha et al,2016).

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Further, we will summarize and review the experiments we consider to be relevant for our topic.

3.1 A closer look over microbial community development

Rumberger et al (2007) conducted their research on an orchard site that was originally planted with apple trees around 1910 and then replanted in 1981 with trees grafted on M.9/M.106 and M.9/M.111 rootstocks (M.111 and M.106 roots with an M.9 interstem). The second planting established poorly and exhibited many symptoms of ARD (Mai et al., 1994). Rumberger et al (2007) argue that using ARD- tolerant rootstocks is an emerging control strategy. Therefore, they studied the bacterial, fungal, and oomycetes populations in the rhizosphere of five rootstock cultivars (M.7, M.26, G.16, G.30 and CG.6210) “planted into the old tree row or grass lanes of a previous orchard in Ithaca, NY, to better understand the role of rhizosphere microbial communities in the prevalence and control of ARD”. Their observations after a period of 3 years, revealed that microbial densities were highest in July, lower in May and lowest in September. Moreover, the study showed that the composition of bacterial and fungal communities in the rhizosphere was highly variable and changed over seasons and years, as assessed by terminal restriction fragment length polymorphism (T- RFLP) analyses (Rumberger et al, 2007). Their research paid attention at the changes in terms of fungal rhizosphere communities, which from initial differences between the planting positions 2 years later, after the trees were replanted, they converged. At the same time, the bacterial rhizosphere community maintained its difference in numbers between the planting positions, even 3 years after the orchard was replanted.

Figure 1 - fingerprints of the bacterial community in rhizosphere soil (reproduced from Rumberger et al, 2007)

In their study, Rumberger et al (2007) observed that just as mentioned before by Catska et al. (1982), the densities of Pseudomonas in the apple rhizosphere decreased over years after replanting, whereas population shifts may be related to changes in soil moisture, soil temperature, rhizodeposition and/or root turnover (Yao et al., 2006b).

Their conclusion was that tree growth and yield data obtained from the studied orchard (Rumberger et al., 2004; Leinfelder and Merwin, 2006) suggest that “avoiding replanting into the old tree rows coupled with the use of tolerant rootstocks are useful strategies for reducing ARD in replanted orchards”. Furthermore, they found that the susceptible rootstocks, M.26 and M.7, supported higher densities of culturable bacteria and fungi in their rhizosphere than the rootstocks G.16, G.30 and CG.6210.

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

3.2 Wheat - the chief mediator

Apple replant disease proved to be a major impediment to organic orchard production systems. (Hoagland et al,2011). Because studies shown that it might be caused by soil-borne pathogens and parasites that are built in the soil of an orchard over time and due to the consequences of this dieses, many orchardists withdrawn their organic certification and used pre-plant fumigation to remediate soil-borne pathogens prior to planting new apple trees (Hoagland et al,2012). As an alternative to chemical products, research over the positive effects of planting wheat prior to planting apple trees was conducted.1 Trials revealed that “beneficial soil microbial communities” Figure 2 - Apple growth in pot previously planted to wheat (control left, organic wheat cultivar right) (July,2009); reproduced were increased after wheat was planted in the orchard from Hoagland et al (2011) soils, which resulted in suppressing soil-borne pathogens and visible improvements in apple seedling health. Wheat varieties bred under organic conditions had the best results, as Hoagland et al (2011) noted upon their research. The conclusion of their trials was that “including only one year of annual wheat cultivation after removal of an existing apple orchard can increase beneficial soil microbial species, suppress soil- borne pathogens and parasites, and improve the establishment and productivity of newly apple planted trees. These results support the hypothesis that modification of soil microbial community composition likely plays a role in disease suppression following cover crop cultivation”. Figure 3-Impact of wheat cultivation on (reproduced from Hoagland et al,2011)

3.2 Brassica seed meal amendments as alternative to soil fumigation

In the early ‘90s, Dr. Mark Mazzola joined the Agricultural Research Laboratory in Wenatchee, Washington to focus his research on control methods of the ARD2. Over years, he conducted several field trials using and comparing different strategies to fight replant disease. He noticed that fumigation with chemicals, such as Telone C-17, only provides short-lived control of harmful soil organisms, while

1 Hoagland, L., Mazzola, M., Murphy, K.M., Jones, S.S., 2012. Wheat varietal selection and annual vs. perennial growth habit impact soil microbial community and apple replant disease suppression. Organic Seed Alliance Conference, Port Townsend, WA. pp. 13-15 2 http://www.goodfruit.com/new-replant-disease-treatment Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma there are other alternatives for” longer lasting effects and even greater benefits than fumigation in terms of both tree growth and fruit yields”.

One of the solution Dr. Mazzola found to be effective is Brassica seed meal amendment (SM) that can provide control of numerous plant pests through generation of biologically active glucosinolate hydrolysis products or indirectly via transformation and activity of the resident soil biology (Mazzola&Zhao, 2010). In Mazzola et al. (2014) it is described how field trials were conducted to determine the effect of SM formulation, moment of application and apple rootstock on their efficiency against ARD. In their study, they used treatment plots of 10,7m/2m, with five replicates per treatment, comparing preplant soil fumigation (using Telone-C17) with Brassica SM formulations. As presented by Mazzola et al. (2014), tree performance in SM-amended soil was “commonly superior to that in fumigated soil at the end of four seasons”. Moreover, they observed an increased resistance to reinfestation in SM- amended soils and that the rhizosphere microbiome gained “unique bacterial and fungal profiles, including microbial elements previously associated with suppression of plant pathogens”

The study concluded that using Brassica SM formulations apple replant disease can be fought as shown by the growth of the trees and increased yields. Mazzola’s research also showed that the SM applications can provide weed control, as well as (like the metagenome analyses revealed) generating higher populations of bacteria that can metabolize toxic organic compounds (this may enable degradation of pesticides applied to the orchard).

reproduced from Mazzola et al. (2014) 1

3.3 Herbie – an efficient fighter against soil borne pathogens

Between 2004 and 2009 the Dutch company Thatchtec developed, in collaboration with Wageningen UR, a new method for biological soil decontamination(sRset). The method consists of the introduction of 100% plant-based Herbie-granulates (or liquid) into the soil, followed by covering the soil with foil for 3 to 4 weeks. According to the tests the company made, it was shown that after this period, the ground is usually free of nasty diseases caused by damaging nematodes, molds and insects (in Annex 1 are described the conditions and results of the field tests on apple trees, conducted by Laimburg Research Centre for Agriculture and Forestry, Italy in 2016; the trials included the use of different methods and products such as steaming, solarisation, chemical and biofumigants – including Herbie). Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Thatchtec, through the Soil Resetting division, started in 2014 a close collaboration with Fleuren Tree Nursery in Kessel, Limburg province (The Netherlands), conducting a field trial with a duration of two years. The aim of the experiment was to reproduce the tests described by Mazzola (2010;2014;2015) using Herbie as mediation product in apple replant disease control. Plant behavior was closely observed and the results were visible positive in the areas where the soil was amended.

picture of apple trial 2014-2016 1- photo summer 2016 by H.Meints

In March 2017, a new field trial was agreed for the same location but with more ambitious objectives. In the following two years, a total surface of 990m2 will be divided into eight lots of 8m per 15m, with an added buffer zone of 2m per 15m, while the dosage of Herbie per treatment plot will be 322 kg, plus a half dosage plot. The control area will be left untreated. Comparing with the reported figures in Mazzola (2014), the selected surface for testing plots at Fleuren Boon, is by far larger. It was decided on purpose to use these bigger scales aiming at an increased validity for the future test results, as Thatchtec reported. Furthermore, a closer attention will be paid at the soil biology and tree performance (growth and yields) during different seasons. The hypothesis is that creating the proper anaerobic conditions in the soil depends on the outside temperature, period of the year and the moment of replanting. Therefore, the first planting moment(PL1) will take place four weeks after removing the sealing foil3 . However, the second moment of planting (PL2) has been chosen for April 2018.

3 The trial will use foil covering periods of 4,8 and 12 weeks Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

satellite pictures of the tested area 1- Meints (2017)

The major difference between this trial session and the previously conducted one in 2014, is that now temperature will play a key role (observing the results under high to low values) and the dosage will vary (decrease) from 2,4 to 1,2 kg / m2) . One of the questions that this research is willing to answer according to Thatchtec is: when can the previous test results be obtained along the trial period (in relation with the timeframe and external factors)?

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma 4. Conclusion and recommendations

In the past decades, several researchers focused their attention on identifying the causes of Apple Replant Disease, along with finding new strategies to prevent and control this important threat to fruit production. From leaving the land fallow, using rotation and control crops to soil fumigation and organic amendments, all has been considered over time. Nowadays, there is a visible tendency on using environmental friendly solutions, along with an increase in banning regulation regarding the chemical products used in EU agriculture sector. Therefore, solutions such as Brassica seed meal soil amendments developed by Mark Mazzola, or Herbie invented by Thatchtec in The Netherlands are the proof that alternatives exist and can be efficient. However, like any other practice, they all have limitations in terms of knowledge and it is mandatory to conduct further research in order to improve their approach. Both Mazzola and Thatchtec aim at increasing the performance of SM and respectively Herbie, when it comes to dosage, waiting time (till removing the sealing foil) and moment of planting the trees. By using larger surfaces for the field trials, as well as testing the method in different times of the year, together with multi-DNA tests (to monitor the soil biodiversity), all these give a valuable insight over the complexity of replant disease. Thus, for fighting it we need the proper (and as complete as possible) knowledge, which can only be gained by exploring, experimenting, (re)inventing till the field tests reach saturation. As Kelderer et al (2017) describes in their report over the Core Organic 2 Project Bio-Incrop in Laimburg(see also Annex) and previously discussed above, using soil amendments like Brassica SM or Herbie developed by Thatchtec, has resulted in an almost 100% pathogen suppression and significant increase in trunk circumference and yield. However, in the case of Herbie and particularly in the trials conducted at Fleuren Tree Nursery in Baarlo, experiments are pushed to their extremes trying to monitories the method’s efficiency and limitations, regarding time frames, larger range of temperature and dosage. What differentiate this later trial from the ones conducted by Mark Mazzola in the US, is that at Fleuren, testing lots are bigger and a special attention is given to replicating the trials in various season conditions. So far, the results obtained gave a positive trend and special attention should be paid not only to the unpredictable weather conditions and temperature from the first half of the year (that were obviously different from the usual values) that can affect the trials, but also try to observe and monitor the soil biodiversity along the tests, complementary to the plant behavior. This way we will not only be able to draw conclusions on the apple tree health but also on the changes that occur in the soil and how can Herbie influence the development of soil communities. Another suggestion for future tests and research could be the usage of mixt disease control methods, such as sRset and compost, to observe whether they can be complementary or not. It would be interesting to investigate as well if adding compost to the disinfected soil, will have any effect on the dosage of Herbie applied for the treated surfaces, the plant development or yield. This aspect can influence directly the commercial side of using sRset as a viable and accessible method to a larger scale.

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma 5 Field trials photos

Field trial 2017-2019 1 – photo Toma (2017)

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Field trial 2017-2019 2 - applying and incorporating Herbie - photo Toma (2017)

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Field trial 2017-2019 3 - testing the incorporation level, digging and covering with foil - photo Toma (2017) Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma 6. Annex 14

Field test results over apple tree performance and soil analysis in the Northern part of Italy.

Department of Ecological Agriculture - VZ Laimburg – 2016

File: BioIncrop Year of experiment: 2016 Subject: Ground fatigue field test Test facility: Block 93 Variety / Subsistence: Pink Lady M9 Planting distance 3,2 x 1 m Experiment Design: 12 variants, 4 replicates of 13-15 trees per 2 edge trees A soil - weary experimental plant (previous variety: Braeburn on M9, planting distance 3,2 x 1 m, planting year 1998) was carried out with different measures and different products.

Test subjects:

4 All the data and graphics in the current annex were translated and reproduced from the original report provided by Laimburg Research Centre for Agriculture and Forestry, Italy to Thatchtec BV Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Description:

Compost analyzes:

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

The compost was made of organic material and wood shavings - 3 kg / tree and was added to the plant hole during planting.

Fertilizing the plant 2016: 04.04.2016 Nitramoncal 29 N kg/ha 04.05.2016 Fertigonia 18-18-18 10,3 N kg/ha 20.06.2016 Fertigonia 18-18-18 3,4 N kg/ha

Product description: Herbie 82 (dry plant-based product) It was used for introducing it into the moist soil and hermetically covered with foil upon proper mixing. The expected result was to create anaerobic conditions and enable fermentation process into the soil.

Dates from Thatchtec B.V over Herbie: Analyzes of Laimburg Agricultural Chemistry Laboratory:

Ash: 4-5% Trockenmasse (%) 89,6 Dry weight: 90-95% Feuchtigkeit (%) 10,4 Protein: 20-26% Asche (% FM) 6,5 Fiber: >10% Organische Substanz (% FM) 83,1 Sugars: 4-6% Stickstoff (N) (% m/m) 2,58 Starches: 2-3% C/N-Verhätlnis 19 Ph: 4,5-5 Wasserlösliche Salze (mg/100 g) 810 Arsen (As) (mg/kg FM) 1,1 Eisen (Fe) (g/kg FM) 0,07 Aluminium (Al) (g/kg FM) 0,02 Mangan (Mn) (mg/kg FM) 31,07 Kupfer (Cu) (mg/kg FM) 6,31 Zink (Zn) (mg/kg FM) 29,06 Chrom (Cr) (mg/kg FM) 1,17 Nickel (Ni) (mg/kg FM) 0,62 Blei (Pb) (mg/kg FM) < 0.01 Cobalt (Co) (mg/kg FM) < 0.01 Cadmium (Cd) (mg/kg FM) 0,07 Quecksilber (Hg) (mg/kg FM) 0,005

What has been done: - 1 month before planting, 3.4 kg / m² of Herbie was incorporated in the tree strip in the damp soil

- The soil was covered with film and well-sealed

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

In 2015, the 2nd planting was carried out on the solarized area and in the control area.

Table soil analysis on 11.03.2015:

Evaluations: Figure 3: Drive length measurement in cm in the open air 1. Measurement: 14.01.2015 2. Measurement: 10.11.2015

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Figure 4: Stem growth measurements (diameter) in mm in the open air 1. Measurement after planting: 20.06.2014 2. Measurement in autumn: 19.11.2014 3. Measurement in the autumn: 10.11.2015 4. Measurement in autumn: 06.12.2016

Figure 5: Harvest 03.11.2016 Number of apples / tree

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

Figure 6: Harvest 03.11.2016 KG Apples / tree

Apple Replant Disease – Theory versus practice, an overview of known controlling methods H. Meints & A. Toma

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Brown PD, Morra MJ (1997) Control of soilborne plant pests using glucosinolate-containing plants. Adv Agron 61:167– 231

Brown J, Davis JB, Erickson DA, Seip L, Gosselin T (2004) Registration of ‘Pacific Gold’ condiment yellow mustard. Crop Sci 44:2271–2272

Catska, V., Vancˇura, V., Hudska´ , G., Prˇikryl, Z., 1982. Rhizosphere micro-organisms in relation to the apple replant problem. Plant and Soil 69, 187–197.B

Council Directive 91/676/EEC (1991) Protection of waters against pollution caused by nitrates from agricultural sources. Off J L 375:1–8

Dickerson GW (1999) Damping-off and root rot. BioCycle 40:62–63

Hoagland et al., 2011.Biological Mediation of Apple Replant Disease in Organic Apple Orchards

Hoagland, L., Mazzola, M., Murphy, K.M., Jones, S.S., 2012. Wheat varietal selection and annual vs. perennial growth habit impact soil microbial community and apple replant disease suppression. Organic Seed Alliance Conference, Port Townsend, WA. pp. 13-15

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